the word 'unshakably' is a modern english formation built upon the old english verb 'shake,' which descends from the proto-germanic skakaną, meaning "to shake, swing." the negative prefix 'un-,' also of old english and proto-germanic heritage, is added to create 'unshakeable,' an adjective meaning "not able to be shaken." the final adverbial suffix '-ably' combines the latin-derived '-able,' indicating capability, with the english '-ly,' which forms adverbs. thus, the literal progression from "not able to be moved physically" evolves into the abstract modern sense of acting with immovable firmness, conviction, or certainty.

Structure: un (not) + shake (to move) + ably (in a manner of) - un: a prefix of old english origin, meaning "not," used to form negatives. - shake: a verb of old english origin (from sceacan), meaning to move to and fro with quick, forceful movements. - ably: an adverbial suffix of latin origin (via old french -able + -ly), meaning "in a manner that can be [verb]ed" or "in a [adjective] manner."