Merriam-Webster's Word of the Day

Merriam-Webster's Word of the Day for May 21, 2026 is:





lacuna • \luh-KOO-nuh\ • noun

Lacuna is a formal word that refers to a gap or blank space in something—in other words, a missing part. When used with respect to biology, lacuna also refers to a small cavity, pit, or discontinuity in an anatomical structure.

// The absence of hemlock pollen from one stretch of the fossil record is a notable lacuna that suggests the tree may have once suffered from some type of blight that nearly wiped out the species.

// An osteocyte is a cell that is isolated in a lacuna of bone.

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Examples:

“At the heart of every biography ... lies a lacuna—something unknowable, no matter how candid or heavily documented the subject, no matter how familiar or diligent the biographer.” — Casey Cep, The New Yorker, 14 Apr. 2025





Did you know?

If you find yourself drawing a blank when it comes to the definition of lacuna, it might help to imagine drawing water instead, ideally from a lake or lagoon. Lacuna, lake, and lagoon all come ultimately from lacus, the Latin word for “lake.” Latin speakers modified lacus into lacuna to form a word meaning “pit,” “gap,” or “pool.” When English speakers borrowed the term in the 17th century, they used it to refer to a figurative gap in or missing portion of something, such as information or text. (Note that lacuna comes with two plural options: the Latin lacunae \luh-KYOO-nee\ or \luh-KOO-nye\, or the anglicized lacunas \luh-KOO-nuz\.) Lagoon, meanwhile, hewed closer to the Latin lacuna, referring first to a shallow sound, channel, or pond near or connected to a larger body of water, and later to a shallow artificial pool or pond.

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





cordial • \KOR-jul\ • adjective

Cordial describes someone or something that is politely pleasant and friendly.

// All the guests were assembled and given a cordial greeting by the host.

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Examples:

“The Burnside post office is a small one-­room wooden building profusely planted with flowers all around it. ... One enters a tiny vestibule and pushes a buzzer, which brings Christine out of the house, brushing by you into the ‘office’ proper, where she opens the counter window and, with a smile and a toss of her hair, says, in a cordial tone, ‘Now, my dear, what can I do for you?’” — Robert Finch, Summers in Squid Tickle: A Newfoundland Odyssey, 2025





Did you know?

The Latin root cord- (or cor) is at the heart of the connection between cordial, concord (meaning “harmony”), and discord (meaning “conflict”). Cord- means “heart,” and each of these cord- descendants has something to do with the heart, at least figuratively. Concord, which comes from com- (meaning “together” or “with”) plus -cord, suggests that one heart is with another. Discord combines the prefix dis- (meaning “apart”) with -cord to imply that hearts are apart. Hundreds of years ago, cordial could mean simply “of or relating to the (literal) heart” (the -ial is simply an adjective suffix) but today anything described as cordial—be it a friendly welcome, a compliment, or an agreement—comes from the heart in a figurative sense. Cordial is also used as a noun to refer to a usually sweet liqueur, the name being inspired by the idea that a cordial invigorates the heart.

Merriam-Webster's Word of the Day for May 19, 2026 is:





demeanor • \dih-MEE-ner\ • noun

Demeanor refers to someone’s outward manner and behavior toward others.

// The teacher’s calm demeanor put the classroom at ease.

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Examples:

“At home, your demeanor impacts your family more than you realize. Your kids feed off your energy. If you’re engaged, positive, and present, they feel it.” — Brandon Brigman, The Rockdale Citizen (Conyers, Georgia), 30 Mar. 2026





Did you know?

The history of demeanor begins with a threat: the word has its roots in Latin minārī, meaning “to threaten.” A form of that word was used in contexts having to do with driving animals—that is, impelling them to move—and from this word came more recent French ancestors having to do with leading, guiding, and behaving. By the 14th century, English had adopted a word out of this lineage: the verb demean meaning “to conduct or behave (oneself) usually in a proper manner.” (Another demean, defined as “to lower in character, status, or reputation,” entered the language later by way of the mean that has to do with being cruel.) The noun demeanor was formed in the following century through the addition of the suffix -or.

Merriam-Webster's Word of the Day for May 18, 2026 is:





vindicate • \VIN-duh-kayt\ • verb

To vindicate someone is to show that they are not guilty. Vindicate can also mean “to show that someone or something that has been criticized or doubted is correct, true, or reasonable.”

// A series of testimonies helped vindicate the defendant.

// Their much-maligned approach to the problem has now been vindicated by these positive results.

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Examples:

“He [Bob Dylan] never expressed embarrassment over the dismal commercial failure of his would-be cinematic masterpiece, Renaldo and Clara, even after the film’s financers, Warner Bros., warned Dylan that the film’s nearly five hour running time would ensure its failure (which would prove true). Dylan insisted that the film needed every frame. And who knows, art history may vindicate him.” — Ron Rosenbaum, Bob Dylan: Things Have Changed, 2025





Did you know?

It’s hard not to marvel at the rich history of vindicate. Vindicate, which has been used in English since at least the mid-16th century, comes from a form of the Latin verb vindicare, meaning “to set free, avenge, or lay claim to.” Vindicare, in turn, comes from vindex, a noun meaning “claimant” or “avenger.” Truly, vindex has proven to be an incredible hulk of a word progenitor over the centuries. Other descendants of this “avenger” assembled in English include avenge itself, revenge, vengeance, vendetta, and vindictive.

Merriam-Webster's Word of the Day for May 17, 2026 is:





affable • \AF-uh-bul\ • adjective

Affable describes someone who is friendly and easy to talk to. It can also describe something, such as someone’s personality, that is characterized by ease and friendliness.

// The restaurant’s affable owner can be seen most nights welcoming his guests and making light conversation.

// In the hallways, the principal has an affable demeanor; however, when called to her office, students know she is all about business.

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Examples:

“Ray Naranjo is a Native American chef from Santa Clara Pueblo in northern New Mexico. He’s a big, affable man with a wide, warm smile, built more for a football field than his food truck, Manko.” — Michael Shaikh, The Last Sweet Bite: Stories and Recipes of Culinary Heritage Lost and Found, 2025





Did you know?

There is nothing in the meaning of affable (“friendly and easy to talk to”), nor in its etymology (the word traces back to the Latin verb affārī, meaning “to speak to, address”), to suggest it is more properly applied to men than to women, but English-speaking people behave as though it is. This was not always true; in the 16th through the 19th centuries, it was not uncommon to see the word describing women, but no more. We once surveyed all the cases in which a single newspaper used affable over a 12-month period. The word occurred in 102 articles, and in 4 occurrences it described women, while in 85 occurrences it described men (in the other cases affable was used to describe a conga line, email, musical compositions by Robert Ward, cats in general, and one male dog). None of this need affect your use of the term. You should feel free to apply it in whatever way seems suitable. Think of this more as a reminder that the currents of our language are deep and occasionally mysterious, gently nudging us along paths we don’t even see.