assiduous

American  

[uh-sij-oo-uhs] / əˈsɪdʒ u əs /

adjective

1. constant in application or effort; working diligently at a task; persevering; industrious; meticulous.

   an assiduous student.

   Synonyms:

   sedulous, diligent, studious

   Antonyms:

   lazy, inconstant

2. constant; unremitting.

   assiduous reading.

   Synonyms:

   persistent, tireless, continuous

   Antonyms:

   lazy, inconstant

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assiduous British  

/ əˈsɪdjʊəs /

adjective

1. hard-working; persevering

   an assiduous researcher

2. undertaken with perseverance and care

   assiduous editing

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Other Word Forms

• assiduously adverb
• assiduousness noun
• unassiduous adjective
• unassiduousness noun

Etymology

Origin of assiduous

First recorded in 1530–40; from Latin assiduus, equivalent to assid(ēre) “to sit near or beside, dwell close to” ( assess ) + -uus adjective suffix; -ous

Example Sentences

While he is destined to become the supreme governor of the Church of England, he isn’t an assiduous churchgoer.

From The Wall Street Journal

The U.S. assessment attributed the escapes to mismanagement by Syria’s government and a lack of assiduous custody of the camp’s large security perimeter, the U.S. officials said.

From The Wall Street Journal

Always an assiduous public-image crafter, George Washington paid meticulous attention to both his personal appearance and that of his beloved Mount Vernon estate, where he constantly received friends, associates and admirers.

From The Wall Street Journal

Norris' success in 2025 was the consequence of a big step in performance in the second half of the season, after assiduous work with his team on improving following a difficult first few races.

From BBC

Powell’s assiduous outreach to his colleagues gives him a good overview of where the proverbial bodies are buried, giving colleagues ample time to voice their objections.

From Barron's

Related Words

• diligent
• exacting
• indefatigable
• laborious
• scrupulous
• zealous