Deepfake refers to an image or recording that has been convincingly altered and manipulated to misrepresent someone as doing or saying something that was not actually done or said.

// The leaked video incriminating the school's dean was discovered to be a deepfake.

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"Overall, the deepfakes are impressive, if not maybe a tad uncanny, showing a near-perfect replica of how Jagger, Keith Richards and Ronnie Wood looked in the late '70s." — Ethan Millman, The Hollywood Reporter, 14 May 2026

The old maxim "things aren’t always as they seem" seems more true than ever in the age of deepfakes. A deepfake is an image, or a video or audio recording, that has been edited using an algorithm to replace the person in the original with someone else (especially a public figure) in a way that makes it look authentic. The fake in deepfake is transparent: deepfakes are not real. The deep is less self-explanatory: this half of the term is specifically influenced by deep learning—that is, machine learning using artificial neural networks with multiple layers of algorithms.

Someone or something described as acquisitive is characterized by a strong desire to own or acquire more things.

// The game aims to teach middle schoolers to balance their acquisitive instincts with a consideration of what will benefit society as a whole.

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“The Athenians, say the Corinthians in Thucydides’s history, are innovative, adventurous, swift to action, acquisitive and keen to expand their empire.” — Edith Hall, The Daily Telegraph (London), 2 May 2026

While acquisitive is a useful synonym of the likes of greedy and avaricious, it’s relatively unknown compared to its more popular lexical relations, acquire and acquisition. The former of that pair is most often used to mean “to get as one’s own,” as in “skills acquired through practice”; the latter refers either to the act of acquiring something, as in “the acquisition of skills,” or to something acquired or gained, as in “the museum’s recent acquisitions.” All three have as their ultimate source the Latin word acquīrere, meaning “to acquire.” While acquire and acquisition have both been in use since the 15th century, acquisitive is a bit younger. The word has a somewhat rare use meaning “capable of acquiring” that dates to the late 16th century, but its “greedy” meaning dates only to the early 19th century.

Semiquincentennial refers to a 250th anniversary or its celebration. The word can also be used as an adjective to describe something related to or associated with such an anniversary or its celebration, as in “semiquincentennial festivities.”

// The town’s annual fireworks show promises to be even more spectacular than usual in honor of the nation’s semiquincentennial.

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“July 4, 2026 marks the nation’s semiquincentennial—its 250th birthday since the signing of the Declaration of Independence.” — Kathryn Palmer, USA Today, 13 June 2025

Everyone knows that if you stick a feather in your hat for, say, a Fourth of July celebration, it is called “macaroni.” But what does a Yankee Doodle Dandy call the celebration itself, specifically when it marks the 250th year since the nation’s founding? Such a special day calls for a special word and semiquincentennial fits the bill, as it does for any anniversary of the same esteemed and venerable vintage. If the word’s mouthful of seven syllables overwhelms, it’s simple to break down. The prefix semi- here means “half in quantity or value,” while quincentennial refers to a whopping 500th anniversary or its celebration. (Quin- comes from the Latin word quinque, meaning “five,” and centennial comes in part from the Latin centum, meaning “hundred.”) Hence a semiquincentennial is celebrated precisely halfway en route to a quincentennial. May knowing this etymology be a feather in your cap at your semiquincentennial BBQ.

Corrode means "to slowly break apart and destroy (metal, an object, etc.) through a chemical process" or "to undergo such a process." It is also used as a synonym of undermine to mean "to gradually destroy or weaken."

// Several sections of the pipe have corroded and will need to be replaced.

// Years of lies and secrets had corroded their relationship.

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"Each piece is made of durable steel with a powder coating that won’t rust, fade, or corrode in the weather." — Shea Simmons, Southern Living, 29 Apr. 2026

Corrode comes from the Latin verb corrōdere, meaning "to gnaw or chew up." Corrōdere, in turn, combines the prefix cor- (used here as an intensifier with the meaning of "completely") with the verb rōdere ("to gnaw"). (You may recognize another rōdere descendent, rodent, as a word for members of an order of gnaw-happy mammals.) At one time, corrode was used to literally indicate the action of gnawing away, as in "woodworms corroded the wood." But it is the more figurative senses from the action of gnawing or eating away that have persisted, as in "salt water corroded the iron" or "a lack of transparency by local officials is corroding public trust."

Someone or something described as sagacious has or shows an ability to understand difficult ideas and situations and to make good decisions. Sagacious may be considered a formal synonym of wise and discerning.

// Student reviews paint the writing professor as a sagacious mentor and a compassionate teacher.

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“It’s a lyrical truism with the kind of wisdom that feels particularly sagacious only within the context of pop music: Of course breaking up is hard to do, but when expressed by [Neil] Sedaka at the end of each verse (and the beginning of each bridge) of his pained plea to his partner to ‘give our love another try,’ it feels like hard-earned insight.” — Andrew Unterberger, Billboard, 2 Mar. 2026

You might expect, wise word wonk that you are, that the word sagacious is etymologically linked with sage, which, as an adjective, means “wise” or, as a noun, “a wise person.” However, despite similarities of spelling, sound, and sense, the two words are not closely related. Sagacious comes from sagire, a Latin verb meaning “to perceive keenly,” while sage comes from a different Latin verb, sapere, which means “to taste,” “to have good taste,” or “to be wise.” Sagacious entered the English language around the beginning of the 17th century and, for some decades, referred to perceptiveness of sight, taste, and especially, smell, hewing close to its Latin ancestor. It has largely lost the sense (no pun intended) of sensory keenness, and now almost exclusively describes someone or something displaying keen, discerning judgment.

A nabob is a very rich or important person.

// The upscale hotel downtown is a popular meeting spot for the city’s corporate nabobs.

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“NBA nabobs were dismayed by the player empowerment era, where players dictated trades or abandoned teams via free agency.” — Christopher L. Gasper, The Boston Globe, 26 Jan. 2025

In India’s Mogul Empire, founded in the 16th century, provincial governors carried the Urdu title of nawāb. In 1612, Captain Robert Coverte published a report of his “discovery” of “the Great Mogoll, a prince not till now knowne to our English nation.” The Captain informed the English-speaking world that “An earle is called a Nawbob,” thereby introducing the English version of the word. Nabob, as it later came to be spelled, gained its extended sense of “a prominent person” in the 18th century, when it was applied sarcastically to British officials of the East India Company returning home after amassing great wealth in Asia. But the word was most famously used by Vice President Spiro Agnew, in a 1970 speech written by William Safire, when he referred to critical members of the news media as “nattering nabobs of negativism.”

To be bereft is to be deprived or robbed of something, or to lack something that you need, want, or expect. Bereft is also used as a synonym of bereaved.

// They appear to be completely bereft of new ideas.

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"... this morning when I was going out to play in the gardens, I went to put on my favorite baseball cap since the sun was hot and, being bereft of my own natural covering, I wished to avoid a sun-scorched scalp." — Dick Brooks, The Daily Gazette (Schenectady, New York), 7 May 2026

In Old English, the verb berēafian meant "to deprive of something." The modern equivalent (and descendant) of berēafian is bereave, a verb used to say that one has deprived or stripped someone of something, often suddenly and unexpectedly, and sometimes by force. Bereft comes from the past participle of bereave; Shakespeare uses the participle in The Merchant of Venice, when Bassanio tells Portia, "Madam, you have bereft me of all words." But by Shakespeare's day bereft was also being used as an adjective. The Bard uses it in The Taming of the Shrew, as a newly obedient and docile Katharina declares, "A woman mov'd is like a fountain troubled—muddy, … thick, bereft of beauty."

Umami refers to the taste sensation that is produced by several amino acids and nucleotides and that has a rich or meaty flavor characteristic of cheese, cooked meat, mushrooms, soy, and ripe tomatoes.

// The chef’s secret ingredient added the perfect burst of umami to the signature dish.

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"This recipe uses a classic marble cake technique to swirl rich layers of cinnamon into a fluffy olive oil-scented loaf cake. It’s topped with a malted milk glaze for a punch of umami, but you can skip it entirely or substitute a simple vanilla glaze." — Tanya Bush, Will This Make You Happy: Stories & Recipes from a Year of Baking, 2026

Japanese scientist Kikunae Ikeda is credited with identifying as a distinct taste the savory flavor of the amino acid glutamic acid, which he first noticed in soup stocks made with seaweed. This fifth basic taste—alongside sweet, sour, salty, and bitter—was named umami, meaning "savoriness" in Japanese. Umami can be experienced in foods such as mushrooms, anchovies, and mature cheeses, as well as in foods enhanced with monosodium glutamate, or MSG, a sodium salt derived from glutamic acid.

To gainsay something is to deny or disagree with it, or to show or say that it is not true. Gainsay is a formal word usually used in negative statements.

// Although the defendant initially denied involvement in the incident, there was no gainsaying the evidence that the prosecutor presented at the trial.

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“Whatever you think of it, there’s no gainsaying the fact that ‘The Sound of Music’ is a remarkably durable vehicle. It’s frequently produced, and suffered no lasting damage to its reputation from a live NBC performance in 2013 ...” — Don Aucoin, The Boston Globe, 9 Jan. 2026

You might have trouble figuring out the meaning of gainsay if you’re thinking of our modern word gain plus say. It should help to know that the gain part comes to us from the Old English word gēan-, meaning “against” or “in opposition to.” (The familiar verb gain comes from Anglo-French and is unrelated.) In Middle English, gēan- was joined to seyen (“to say”) to form gein-seyen, which led to the modern word gainsay. So when you see gainsay, think “to say against”—that is, “to deny” or “to contradict.”

Oracular is a formal word that can describe something used to forecast or prophesize, or something that resembles or relates to something used for such purposes. Oracular can also describe something that resembles an oracle—a person (such as a priestess of ancient Greece) through whom a deity is believed to speak; in this sense, an oracular statement, voice, etc. conveys wisdom or solemnity.

// A few recordings of the famous speaker still exist, and though his language is formal to the point of sounding almost foreign to the modern listener, the oracular quality of his speech remains effective.

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"The conversation that unfolds is some of [writer Ben] Lerner's most brilliant and daring writing to date, a mad, oracular burst of speech—about technology, parenthood, and dreaming—that flits effortlessly between prose and poetry." — Kevin Lozano, Vulture, 3 Apr. 2026

When the ancient Greeks had questions or problems, they would turn to the gods for answers by consulting an oracle, a person through whom the gods communicated, usually in the form of cryptic verse. Oracle also referred to the god's answer or to the shrine that worshippers approached when seeking advice; the word's root is the Latin verb orare, which means "to speak." English speakers today can use oracle to simply refer to an authoritative pronouncement or to a person who makes such pronouncements—for example, "a designer who is an oracle of fashion." And the related adjective oracular is used in similar contexts: "a designer who is an oracular voice of fashion."