Merriam-Webster's Word of the Day for January 20, 2026 is:

quiddity • \KWID-uh-tee\  • noun

Quiddity refers to the essence of a thing—that is, whatever makes something the type of thing that it is. Quiddity can also refer to a small and usually trivial complaint or criticism, or to a quirk or eccentricity in someone's behavior.

// The novelist’s genius was her unparalleled ability to capture the quiddity of the Maine seacoast in simple prose.

// He portrayed the character's quirks and quiddities with tender playfulness.

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Examples:

“When I was gathering my odes into a book—or rather, piling up my effusions in prose and verse and trying to work out which ones were odes and which weren’t—my friend Carlo gave me a magical concept. He called it ‘the odeness.’ It’s the essential quality, quiddity, … uniqueness of whatever you’re trying to write about. It’s what your ode is attempting to first identify and then celebrate. It’s the odeness of your ode.” — James Parker, The Atlantic, 30 Sept. 2025

Did you know?

When it comes to synonyms of quiddity, the Q’s have it. Consider quintessence, a synonym of the “essence of a thing” meaning of quiddity, and quibble, a synonym of the “trifling point” use. And let’s not forget about quirk: like quiddity, quirk can refer to a person’s eccentricities. Of course, quiddity also comes from a “Q” word, the Latin pronoun quis, which is one of two Latin words for “who” (the other is qui). Quid, the neuter form of quis, led to the Medieval Latin quidditas, which means “essence,” a term that was essential to the development of the English word quiddity.