Merriam-Webster's Word of the Day

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





assiduous • \uh-SIJ-uh-wus\ • adjective

Assiduous is a formal word that means “showing great care, attention, and effort.”

// Thanks to the assiduous efforts of the local land trust over many years, a substantial amount of whip-poor-will habitat is now protected from development.

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Examples:

“My mom was also assiduous about what we would today call food safety, avoiding anything that could possibly cause illness, especially raw meat: ‘Well done’ was the norm for everything, and anything that could possibly go bad was kept in the fridge.” — James Martin, Work in Progress: Confessions of a Busboy, Dishwasher, Caddy, Usher, Factory Worker, Bank Teller, Corporate Tool, and Priest, 2026





Did you know?

While assiduous means “showing great care, attention, and effort,” and in some situations may be an appropriate substitute for careful, it’s got a bit more oomph than careful in that it suggests a dogged or tireless persistence. If you are assiduous in your efforts (or work, research, analysis, training, preparations, etc.) for example, it’s implied that you’re in it for the long haul, or that you have the ability to “sit with” a task or challenge for a considerable amount of time. This idea is fitting given that assiduous comes from the Latin verb assidēre, meaning “to sit beside.”

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





longueur • \lawn-GUR\ • noun

Longueur refers to a boring part of something (such as a book or play). It is usually used in the plural form.

// Though not without its longueurs, the opera came to life in the last act.

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Examples:

“Game 3 of the World Series was a stone-cold thriller, with peaks of high drama and longueurs of exquisitely tense tedium ...” — Steve Rushin, The Atlantic, 2 Nov. 2025





Did you know?

You’ve probably come across long, tedious sections of books, plays, or musical works before, but perhaps you didn’t know there was a word for them. The French borrowing longueur has been doing the job for us since the late 18th century. As in English, French longueurs are tedious passages, with longueur itself literally meaning “length.” An early example of longueur used in an English text is from 18th-century writer Horace Walpole, who wrote in a letter, “Boswell’s book is gossiping; ... but there are woeful longueurs, both about his hero and himself.”

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





indomitable • \in-DAH-muh-tuh-bul\ • adjective

Indomitable is a formal word used to describe something that is impossible to defeat or discourage.

// Juneteenth celebrates the abolition of slavery in the United States, and honors the indomitable spirit of African Americans past and present fighting for justice, liberation, and the fulfillment of this nation’s ideals.

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Examples:

“During his legendary NBA career, Michael Jordan was renowned not only for his athleticism and skill but also for his indomitable will to win.” – Chicago Tribune, 1 Apr. 2026





Did you know?

At five punchy syllables, indomitable is an imposing word, so it’s inevitable that some are perplexed by this synonym for impregnable. But it’s not so tough once you break it into parts. The prefix in- (spelled im- before b, m, and p) means “not” in an innumerable collection of English words. (How many have you counted so far?) The common suffix -able means “capable of, fit for, or worthy of.” Combine those two English affixes with the Latin verb domitare (“to tame”), and voila: indomitable. Indomitable was first used in English as a synonym of wild, describing—appropriately enough—things that cannot be tamed, but over time the wildness associated with indomitable developed into a specific kind of invulnerable strength.

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





acquiesce • \ak-wee-ESS\ • verb

To acquiesce to something is to accept it, agree with it, or allow it to happen by staying silent or by not arguing. Acquiesce is somewhat formal, and is often used with in or to.

// Eventually, the professor acquiesced to the students’ request to have the seminar’s final class be a potluck lunch.

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Examples:

“It may be just the right time for a chicken burger to become a significant stop on the American burger’s continual evolution—but whether beef-clinging purists will acquiesce to a poultry spin, or cry fowl, remains to be seen.” — Talib Visram, Slate, 6 Apr. 2026





Did you know?

If you’re looking to give your speech a gentle, formal flair, don’t give acquiesce the silent treatment. Essentially meaning “to comply quietly,” acquiesce has as its ultimate source the Latin verb quiēscere, “to be quiet.” (Quiet itself is also a close relation.) Quiēscere can also mean “to repose,” “to fall asleep,” or “to rest,” and when acquiesce arrived in English via French in the early 1600s, it did so with two senses: the familiar “to agree or comply” and the now-obsolete “to rest satisfied.” Herman Melville employed the former in Moby-Dick, when Ahab orders the “confounded” crew to change the Pequod’s course after a storm damages the compasses: “Meanwhile, whatever were his own secret thoughts, Starbuck said nothing, but quietly he issued all requisite orders; while Stubb and Flask—who in some small degree seemed then to be sharing his feelings—likewise unmurmuringly acquiesced.”

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





wifty • \WIF-tee\ • adjective

Wifty, a synonym of ditzy, describes something or someone eccentrically silly or scatterbrained.

// The play features a wifty character who starts out blissfully unaware of the conflict driving the plot but ultimately pulls it together to save the day.

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Examples:

“When he dreams, he dreams about moving to Wyoming, which he has visited with his family. ... Sometimes when he talks about this, it sounds as ordinary and hard-boiled as a real estate appraisal; other times it can sound fantastical and wifty and achingly naive ...” — Susan Orlean, Joyride: A Memoir, 2025





Did you know?

Whence wifty? Wordsmiths have been wondering for a while. The earliest print evidence of wifty comes from the early 20th century, though the word was certainly being used in spoken English before that. The adjective suffix -y is clear enough; when added to another word it can mean “full of” (as in “muddy), “having the character of” (think “waxy”), “tending or inclined to” (as in “sleepy”), etc. So what’s wift? Well, that element could come from whiff, which as a noun can refer to a quick puff or slight gust of air—a person described by the word wifty might also, if unkindly, be called an airhead. Or perhaps the wift is related to waft, “to move or go lightly on a buoyant medium,” if it’s fair to say that the wifty among us have their heads in the clouds. Whatever once may have been known about it, the answer is now blowing in the wind.