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, 2001–2017.