The word "unalterably" is built upon the Latin root alter, meaning "other." This root gave rise to the verb "alter," meaning to make something "other" than it was, i.e., to change it. The addition of the suffix -able creates the adjective "unalterable," describing something that cannot be made "other." Finally, the adverbial suffix -ly is appended to form "unalterably," describing an action performed in an unchangeable manner. The entire construction, layered through Latin, French, and English, logically progresses from the concept of "otherness" to the modern abstract sense of an immutable state or action.

Structure: un (not) + alter (change) + ably (in a manner of) - un: A prefix of Germanic origin (Old English un-), meaning "not." It functions as a negative particle. - alter: A root from Latin alter meaning "other, another, second." It functions as the core verb meaning "to change." - ably: A suffix from Latin -abilis (via Old French -able and -ably), meaning "in a manner that can be." It forms adverbs from adjectives ending in -able.