Cognate (via assidere) to assess.
- Hard-working, diligent or regular (in attendance or work); industrious.
- 1831, Sir Walter Scott, chapter 2, in The Surgeon's Daughter:
- He was officious in the right time and place, quiet as a lamb when his patron seemed inclined to study or to muse, active and assiduous to assist or divert him whenever it seemed to be wished.
- 1880, Henry James, chapter 33, in Washington Square:
- He died after three weeks' illness, during which Mrs. Penniman, as well as his daughter, had been assiduous at his bedside.
- 1917, P. G. Wodehouse, "Bill the Bloodhound" in The Man With Two Left Feet and Other Stories:
- A good deal of assiduous attention had enabled Henry to win this place in her affections.
- 2009, Will Pavia, "Allen Klein, accountant turned manager of the Beatles, dies at 77," The Times (UK), 6 July:
- Klein rose to prominence in the 1960s by assiduous application of accounting methods to the music industry.
- “assiduous” in Douglas Harper, Online Etymology Dictionary, 2001–2020.