Cognate (via assidere) to assess.

• (British) IPA: /əˈsɪdjuːəs/, /əˈsɪd͡ʒuːəs/
• (America) IPA: /əˈsɪd͡ʒu.əs/

assiduous

1. Hard-working, diligent or regular (in attendance or work); industrious.

   Synonyms: meticulous, diligent, sedulous, Thesaurus:industrious

   • 1880, Henry James, chapter 33, in Washington Square‎, Harper & Brothers, →OCLC ↗, page 249 ↗:

     He died after three weeks' illness, during which Mrs. Penniman, as well as his daughter, had been assiduous at his bedside.

• French: assidu
• German: fleißig, geflissen, gewissenhaft
• Italian: assiduo
• Portuguese: assíduo, trabalhador, diligente
• Russian: стара́тельный
• Spanish: asiduo, diligente