Simpatico typically describes two or more people or things with shared qualities, interests, etc. It can also describe someone who is agreeable or likeable.

// Even though they weren’t always simpatico with regard to the direction of their company, the pair managed to be successful partners for more than 35 years.

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“From the early 2010s, when he was a young teen rapper in Chicago ... Chief Keef was flooding his Instagram with self-documentation, all of which is essentially gone now. Enter Eduard Taberner Pérez, an amateur archivist and professional graphic designer, who compiled ‘Sosa Archive,’ a limited-run art book that gathers several thousand photos pulled from Keef’s Instagram, presenting then in visually simpatico grids of 12.” — Jon Caramanica, The New York Times, 5 Mar. 2025

Simpatico, which comes ultimately from the Latin noun sympathia, meaning “sympathy,” was borrowed into English from both the Italian simpatico and Spanish simpatico. In those languages, the word has been chiefly used to describe people who are well-liked or easy to get along with. Early uses of the word in English reflected those of their forebears, as in Henry James’s 1881 novel The Portrait of a Lady, in which one character says of another’s dying cousin, “Ah, he was so simpatico. I’m awfully sorry for you.” In recent years, however, the word has gained an additional sense describing things or people who get along well or work well together.

Protocol most often refers to a system of rules explaining the correct conduct and procedures to be followed in a formal situation; in computer programming a protocol is a set of rules used in formatting data. Protocol can also refer to a plan for a scientific experiment or medical treatment, or to a document that describes the details of a diplomatic treaty.

// What is the proper protocol for declining a job offer?

// My doctor recommended a simplified treatment protocol for my condition.

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"Back in the UK, it's still unclear what kind of royal life, if any, lies ahead for Archie and Lilibet. While they hold their princely and princess titles, bestowed upon them following the death of Queen Elizabeth II, their day-to-day lives in Montecito are a world away from palace protocol." — Faye James, Hello Magazine, 15 July 2025

In Late Greek, the word prōtokollon referred to the first sheet of a papyrus roll bearing the date of its manufacture. In some instances, it consisted of a flyleaf that was glued to the outside of a manuscript's case and provided a description of its contents. Coming from the Greek prefix prōt- ("first") and the verb kollan ("to glue together"), prōtokollon gave us our word protocol. In its earliest uses in the 15th century, the word referred to a record of a document or transaction. By the turn of the 18th century it was being used for the original record or minutes of a diplomatic negotiation, and still later for the etiquette observed by heads of state in ceremonies and relations with other dignitaries. This sense has since extended in meaning to cover any code of proper conduct.

Incisive means "impressively direct and decisive." It is generally applied to either something communicated in a way that is very clear and direct, or to a person who is able to explain difficult ideas clearly and confidently.

// The columnist is known for her incisive commentary on local politics.

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"'Death Becomes Her' might be a combination of an uproarious camp sensibility and the grotesquely macabre, but it also contains incisive social critiques—of impossible beauty standards for women, the difficulties of aging, and the lengths people will go to maintain their youthful looks." — Christopher Wallenberg, The Boston Globe, 1 June 2025

An incisive person doesn’t hem and haw—they get straight to the point. The original meaning of incisive, from around 1600, was "having a cutting edge or piercing point"; the modern meaning of "impressively direct and decisive" has been part of English since the mid-1800s. Incisive is a close relative of incisor, which refers to a front tooth typically adapted for cutting, so it's no surprise that incisive has a specific meaning in dentistry, describing that which is of, relating to, or situated near the incisors. Both incisive and incisor come from the Latin verb caedere, meaning "to cut." English is rich in cuttings from the fruitful stem of caedere: some examples to sink your teeth into are scissors, chisel, incise ("to cut into or engrave"), excise ("to remove by cutting"), incision ("cut" or "gash"), precise ("minutely exact"), and concise ("brief").

Diminution is a formal word that refers to the act or process of becoming less.

// The company is committed to seeing that efforts to scale up production do not result in a diminution of quality.

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“A sense of abasement hovers over the performer of the Super Bowl halftime show. It is slight, but it is there. ... The gig—a live gig—is essentially done for free. It ends, the performer is spirited away, and the multi-million-dollar commercials and multi-million-dollar game resume. It’s popular music as the doula to football. The next morning, everyone makes big talk about history and legend-making; the feeling of diminution lingers.” — Doreen St. Félix, The New Yorker, 10 Feb. 2025

In his late 14th century tragic poem Troilus and Criseyde, Geoffrey Chaucer employed the word diminution, contrasting the verb encrece (“increase”) with the phrase “maken dyminucion” (“make diminution”). Like many words Chaucer used, diminution came to English from Anglo-French, and ultimately from the Latin word deminuere, meaning “to diminish,” which is also an ancestor of the English verb diminish. That word entered the language in the 15th century, and the related noun diminishment, a synonym of diminution, was adopted in the 16th century.

Nebulous is a formal word used to describe something that is difficult to see, understand, or describe—in other words, something indistinct or vague.

// A lot of philosophical concepts can seem nebulous at first, but a good instructor can cut through the jargon and help students see how they apply to day-to-day life.

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“[Rob] Harvilla began to notice the blurred lines of late-Nineties genres as he produced his podcast 60 Songs That Explain the ‘90s and while writing its corresponding book. ‘The late Nineties were a weird, transitional wasteland,’ he says. All of these genres that had such stark lines in the Nineties have now become a more nebulous concept, blending into one supergenre of just ‘Nineties music.’” — Brittany Spanos, Rolling Stone, 21 July 2025

Nebulous may sound otherworldly—after all, it’s related to nebula, which refers to an interstellar cloud of gas or dust—but its mysteriousness is rooted in more earthly unknowns. Both words ultimately come from Latin nebula, meaning “mist, cloud,” and as far back as the 14th century nebulous could mean simply “cloudy” or “foggy.” Nebulous has since the late 17th century been the adjective correlating to nebula (as in “nebulous gas”), but the word is more familiar in its figurative use, where it describes things that are indistinct or vague, as when Teju Cole wrote of an avant-garde photographer who viewed photography as existing “neither in the camera nor in the printed photograph, but in a more nebulous zone.”

Trepidation refers to a feeling of fear that causes someone to hesitate because they think that something bad or unpleasant is going to happen.

// The students felt a sense of trepidation upon being summoned to the principal's office.

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"Met by some with cautious optimism, others with trepidation, and others with doomsday predictions, there is no doubt that AI is here to stay and changing work in ways yet to be fully revealed." — Laurel Donnellan, Forbes, 28 May 2025

If you've ever trembled with fright, you know something of both the sensation and etymology of trepidation. The word comes from the Latin verb trepidare, which means "to tremble." (Trepidare also gave English the verb trepidate, meaning "to feel nervous or apprehensive," but that word is now considered archaic.) Early meanings of trepidation, such as "tremulous motion" or "tremor," reflect its "shaky" origins. Over time, however, those senses gave way to our modern meaning referring to fearful hesitancy.

Undulant describes things that rise and fall in waves, or things that have a wavy form, outline, or surface.

// The exhibit featured a painting with beautiful green strokes that resembled undulant hills.

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“Though tightly bound by our love of books, we bibliophiles are a sundry lot, managing our obsession in a grand variety of ways. We organize by title, by author, by genre, by topic. By color, by height, by width, by depth. … We stack books into attractive still lifes accompanied by a single tulip in a bud vase, or into risky, undulant towers poised to flatten a passing housecat.” — Monica Wood, LitHub.com, 7 May 2024

If you’re looking for an adjective that encapsulates the rising and falling of the briny sea, wave hello to undulant. While not an especially common descriptor, it is useful not only for describing the ocean itself, but for everything from rolling hills to a snake’s sinuous movement to a fever that waxes and wanes. The root of undulant is, perhaps unsurprisingly, unda, a Latin word meaning “wave.” Other English words swimming the wake of unda include inundate, “to cover with a flood,” and undulate, “to form or move in waves.”

To cloister someone or something is to shut the person or thing away from the world.

// The scientist cloistered himself in his laboratory all weekend to finish analyzing data.

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“Now, the past Melbourne High student body president and co-valedictorian is planning to step down Jan. 20 after serving nearly four years as NASA’s administrator. ... ‘My constitution is such that I’m not going to retire. And what I said is, I’m going to cloister myself and write a book. And then, we’ll see what happens,’ [Bill] Nelson, who is now 82, told reporters Wednesday during a roundtable discussion at the Kennedy Space Center Press Site.” — Rick Neale, Florida Today, 19 Dec. 2024

Cloister first entered the English language as a noun in the 13th century, referring then (as it still does) to a convent or monastery. More than three centuries later, English speakers began using the verb cloister to mean “to seclude in or as if in a cloister.” Today, the noun can also refer to the monastic life or to a covered and usually arched passage along or around a court. You may also encounter the adjective cloistered with the meaning “separated from the rest of the world [as if in a cloister],” as in “She leads a private, cloistered life in the country.” Cloister ultimately comes from the Latin verb claudere, meaning “to close.” Other words that can be traced back to the prolific claudere include close, conclude, exclude, include, preclude, seclude, and recluse.

Something may be described as flagrant if it is conspicuously bad—that is, too bad to be ignored.

// In a flagrant violation of the family's code of ethics, someone finished the ice cream and left the empty container in the freezer.

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"'It wasn't such a brilliant thought to sit on an artwork,' Vanessa Carlon, the museum's director, tells the New York Times' Claire Moses. Carlon says the incident highlights just how far people will go to get a good photo, as well as their flagrant lack of accountability. 'These two people decided to escape,' she adds. 'That was the behavior that really offended us.'" — Sonja Anderson, Smithsonian Magazine, 20 June 2025

A flagrant foul in sports involves no flame or literal heat—it's just too conspicuously bad for referees to ignore—but the roots of flagrant are hot, hot, hot. In Latin, flagrāre means "to burn," and flagrans means "flaming" or "fiery" (both carry meanings relating to literal flames as well as the figurative flames of passion). When it was first used in the 16th century, flagrant had the same "flaming, fiery" meaning as flagrans, but by the 18th century it had acquired its current meaning of “conspicuously bad or offensive.” (Another flagrāre descendant in English, conflagration, retained its "fiery" meaning.) Some usage experts warn against using flagrant and blatant interchangeably. While both words apply to noticeable lapses, they are not true synonyms. Blatant (likely from a Latin word meaning “to chatter”) typically describes a person, action, or thing that attracts disapproving attention (e.g., "a blatant grammatical error"), while flagrant carries a heavier connotation of offense often for violated morality (e.g., "flagrant abuse of public office").

Apathy refers either to a lack of feeling or emotion, or to a lack of interest or concern.

// Though the girl’s expression communicated apathy, Gina knew her daughter was actually very pleased at having won the poetry prize.

// While the previous mayor’s administration responded to the community’s needs with little more than apathy, city hall under the new leadership is making real changes.

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“I find myself shrugging a lot more. And answering, ‘That seems true.’ And saying the exact same thing to the opposing argument. ... I’ve found myself concerned about my apparent apathy and disinterest in picking fights. On the flip side, I’m an easier person to be around.” — Mari Andrew, How to Be a Living Thing: Meditations on Intuitive Oysters, Hopeful Doves, and Being a Human in the World, 2025

Once more without feeling! While its siblings antipathy, sympathy, and empathy refer to often strong emotions, whether tender or terrible, apathy is unconcerned with all that. Whether one is feeling blasé, indifferent, or—to use a more recent coinage—meh, apathy is the perfect word for such a lack of passion. At the root of apathy and its kin is páthos, a Greek word meaning “experience, misfortune, or emotion,” which led first to the adjective apathḗs (“not suffering, without passion or feeling, impassive”) and then the noun apatheîa before passing through Latin and Middle French on its way to English. The prefix a- in both means “without.” The other aforementioned páthos descendants are, of course, supplied with their own prefixes that give clues to their respective meanings: anti- (“opposite”), sym- (“at the same time”), and em- (“in” or “within”).