Remorse
Late Middle English: from Old French remors, from medieval Latin remorsus, from Latin remordere 'vex', from re-(expressing intensive force) + mordere 'to bite'. The idea behind remorse is of regret or guilt that eats away at you, prompting you to repent. The word goes back to Latin remordere ‘to annoy, trouble’. The first part of the word, re-, adds intensity, and the second is mordere ‘to bite’. As re- most often means ‘again’ in a word, remorse was literally translated in Middle English as ‘again-bite’. There is a famous English religious work called Agenbite of Inwyt （‘Remorse of Conscience’） written c.1340. James Joyce used the expression in Ulysses (1922), thereby introducing it to a wider audience.
re- 在这里加强语气，mors- 是咬，词源同 mordant, morsel。上面的引文也提到，中古英语曾按 re- 常见的“再次”含义，把它直译为“再咬一次”。这里用咬来比喻持续的后悔或愧疚。
——收入 词语的化石层