Usk, Thomas (ŭsk) [key], d. 1388, English politician and author. He was under-sheriff of London. While in Newgate Prison he wrote Testament of Love, an allegory in prose describing and justifying the political actions that resulted in his imprisonment. The work is useful in dating Chaucer's Troilus and Criseyde, from which it borrows. Usk was executed in 1388.