In general contexts, speculate means "to form ideas or theories about something usually when there are many things not known about it." In contexts relating to business or finance, it means "to invest money in ways that could produce a large profit but that also involve a lot of risk."

// Scientists speculate that the newly discovered exoplanet could host liquid water.

// Their research explores the implications of so many people speculating on the stock market in the years leading up to the Great Depression.

See the entry >

"Bad Bunny wore an all-cream ensemble consisting of a collared shirt and tie, chinos and a sport-inspired jersey bearing the name "Ocasio"—his surname—and the number 64. The significance of the number was not confirmed, but fans were quick to speculate that it referenced his mother's birth year." — Lara Owen, The Independent (United Kingdom), 9 Feb. 2026

It might be said that what separates our species from others is our tendency "to meditate on or ponder a subject." That's the original 16th century meaning of speculate. It's a use not too distant from today's most common sense, which also involves the mind and thinking: when someone speculates about something, they think and make guesses about it, often forming unsubstantiated ideas or theories. But the origins of speculate lie not in thinking but in looking—the word comes from Latin specere, meaning "to look," or "to look at." We don't have to look far to find other specere descendants, and we'll point them out here with some italics: a cursory inspection reveals spectacle, spectrum, specimen, and perspective. Less conspicuous are despise, prospect, and species.