The word 'unremittingly' is built upon the core verb 'remit', which originates from the Latin 'remittere', literally meaning "to send back" or "to slacken." The prefix 'un-' negates this action, creating the adjective 'unremitting' to describe something that does not slacken or abate. The adverbial suffix '-ingly' is then appended, a productive formation in English that converts such descriptive adjectives into adverbs. Thus, the literal progression from "not sending back/slackening" evolves into the modern abstract sense of continuous, relentless action without pause or diminution.

Structure: un (not) + remit (send back, slacken) + ingly (adverb-forming suffix) - un: A prefix of Germanic origin (Old English 'un-'), meaning "not," used to form negatives. - remit: From Latin 'remittere' (re- "back" + mittere "to send"). In English, it carries the sense of sending back, but also of relaxing or abating. - ingly: A compound suffix formed from the present participle suffix '-ing' and the adverbial suffix '-ly', used to form adverbs from present participles or adjectives ending in '-ing'.