unremitting
The origin and history of unremitting.
Etymology
Made up of un- and remitting, from remit (used in the now rare sense of 'diminish, abate'), which comes from Middle English remitten, itself from Latin remittere ('to send, send back'). Compare Old French remettre and remetre and remitter. It is not from a supposed word unremit, and is first recorded in 1728.