the.com/quitter

means Someone who gives up on a task, goal, or commitment before it's finished.

from Straightforward agent-noun formed from the verb 'quit' plus '-er' — 'quit' arrived in English from Old French 'quiter' / 'quitter' (to release, set free, discharge a debt), itself from Medieval Latin 'quietare,' rooted in 'quietus,' meaning calm or at rest. The sense drifted over centuries from 'releasing someone from an obligation' to 'releasing yourself from one' — so a quitter is, etymologically, just someone who declared themselves free of the job before the job was done.