assiduousness

WordReference Random House Learner's Dictionary of American English © 2026

as•sid•u•ous /əˈsɪdʒuəs/   adj. 

1. diligent:
   assiduous studying.
2. working diligently at a task;
   industrious:
   an assiduous student.

as•sid•u•ous•ly, adv. 
as•sid•u•ous•ness, n. [uncountable] See -sid-.

WordReference Random House Unabridged Dictionary of American English © 2026

as•sid•u•ous  (ə sij′o̅o̅ əs), adj. 

1. constant;
   unremitting:
   assiduous reading.
2. constant in application or effort;
   working diligently at a task;
   persevering;
   industrious;
   attentive:
   an assiduous student.

• Latin assiduus, equivalent. to assid(ēre) to sit near, beside, dwell close to (see assess) + -uus deverbal adjective, adjectival suffix; see -ous
• 1530–40

as•sid′u•ous•ly, adv. 
as•sid′u•ous•ness, n. 
Synonyms

• 1. continuous, tireless, persistent.
• 2. studious, diligent, sedulous.

Antonyms

• 1, 2. inconstant, lazy.