as·​sid·​u·​ous | \ ə-ˈsij-wəs How to pronounce assiduous (audio) , -ˈsi-jə- \

Definition of assiduous

: showing great care, attention, and effort : marked by careful unremitting attention or persistent application assiduous planning an assiduous book collector She tended her garden with assiduous attention.

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Other Words from assiduous

assiduously adverb
assiduousness noun

Choose the Right Synonym for assiduous

busy, industrious, diligent, assiduous, sedulous mean actively engaged or occupied. busy chiefly stresses activity as opposed to idleness or leisure. too busy to spend time with the children industrious implies characteristic or habitual devotion to work. industrious employees diligent suggests earnest application to some specific object or pursuit. very diligent in her pursuit of a degree assiduous stresses careful and unremitting application. assiduous practice sedulous implies painstaking and persevering application. a sedulous investigation of the murder

The History of Assiduous

Assiduous came to English directly from the Latin assiduus, an adjective derived from the verb assidēre "to sit beside." To the ancient Romans, assiduus carried meanings ranging from “settled or rooted in place” to “constantly present” to “persistent, unremitting." This last sense was the one borrowed into English four hundred years ago and still used today, often in complimentary phrases such as "an assiduous student" and “assiduous efforts.” In the 18th century, the word took on a mildly pejorative meaning, "obsequious," when used of someone striving to please. This sense has largely passed out of use.

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Judges presiding over assizes (former periodical sessions of the superior courts in English counties) had to be assiduous in assessing how to best address their cases. Not only were their efforts invaluable, but they also served as a fine demonstration of the etymologies of "assiduous," "assess," and "assize." All three of those words derive from the Latin verb assidēre, which is variously translated as "to sit beside," "to take care of," or "to assist in the office of a judge." "Assidēre," in turn, is a composite of the prefix ad- (in this case, meaning "near" or "adjacent to") and sedēre, meaning "to sit."

Examples of assiduous in a Sentence

They were assiduous in their search for all the latest facts and figures. The project required some assiduous planning.
Recent Examples on the Web Be assiduous in your basting until the top of the fish turns opaque. Kitty Greenwald, WSJ, 11 Oct. 2021 Her plight is known only to the most assiduous of historians, but the original authors of the current resolution that would clear Johnson’s name is a group of 13- and 14-year-olds., 18 Aug. 2021 Olson himself took for his idols the easterners John Burroughs and Henry David Thoreau—and, like Thoreau, was an assiduous journal writer, at least during the middle decades of his life. Richard Adams Carey, WSJ, 13 Aug. 2021 By the same token, Barrack was never confronted with a guest who might have a different view of Trump’s personality and management skills, developed through assiduous reporting rather than cronyism. Michael Hiltzik, Los Angeles Times, 21 July 2021 Then Rachel receives a phone call from a nervous whistleblower, a woman who informs her that Mrs. Hyde-White is Trump’s lover, hiding behind assiduous optometry to make frequent visits to the White House. Washington Post, 13 July 2021 As assiduous environmental activists point out, however, the gulfs in apparel brands’ steps to transform their businesses are stark. Lindsey Tramuta, Fortune, 5 July 2021 Broadway veteran Peter Gallagher played Cohen patriarch and Everyman Sandy — an assiduous public defender and Bronx transplant living in Newport Beach, a wealthy enclave of Orange County, with wife Kirsten (Kelly Rowan) and son Seth (Adam Brody). Lauren Pinnington, Vulture, 18 June 2021 Many observers believe Netanyahu harmed Israel’s standing in Washington with his assiduous courtship of Republicans, eroding what had always been a bipartisan relationship with Israel. Laura King, Los Angeles Times, 13 June 2021

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'assiduous.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of assiduous

circa 1552, in the meaning defined above

History and Etymology for assiduous

Latin assiduus, from assidēre to sit beside

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The first known use of assiduous was circa 1552

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Last Updated

16 Oct 2021

Cite this Entry

“Assiduous.” Dictionary, Merriam-Webster, Accessed 20 Oct. 2021.

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More Definitions for assiduous


as·​sid·​u·​ous | \ ə-ˈsi-jə-wəs How to pronounce assiduous (audio) \

Kids Definition of assiduous

: showing great care, attention, and effort They were assiduous in gathering evidence.

Other Words from assiduous

assiduously adverb

More from Merriam-Webster on assiduous

Nglish: Translation of assiduous for Spanish Speakers

Britannica English: Translation of assiduous for Arabic Speakers


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