Unremitting means never letting up for a moment. Unremitting pressure, unremitting rain, unremitting effort.
It is the word for something that offers no pause, which is why it suits pain, pressure and work. The remit in it is an old sense meaning to slacken, which survives in nothing else.
1adjectiveunremittingNever letting up for a moment.
“The soldiers faced unremitting enemy fire for three days.”
unremitting is a quality.
Also accepted in games: unrelenting
Un- plus remitting, from remit in the old sense of slackening or abating.
Proto-Indo-European
*mey- (change)
Latin
remittō — to send, send back
Middle English
remitten
English, today
unremitting
un- + remitting, from remit (in now rare sense of “diminish, abate”), from Middle English remitten, from Latin remittō (“to send, send back”). Compare Old French remettre, remetre, remitter. Not from nonexistent unremit. 1728.
Etymology from Wiktionary, CC BY-SA