the word "unattainable" is a modern english formation built upon the older verb "attain." the core of "attain" comes from the latin verb attinēre, meaning "to hold to, reach," which itself is a compound of ad- ("to") and tenēre ("to hold"). this etymological sense of "holding onto" something evolved into the abstract meaning of "achieving" a goal or state. the suffix -able, indicating capability, was added to form the adjective "attainable." finally, the germanic negative prefix un- was prefixed to create the current meaning, logically constructing the concept of something not capable of being reached or achieved.

Structure: un (not) + attain (achieve) + able (capable of) un: a prefix of germanic origin (old english) meaning "not," used to form negatives. attain: a verb of latin origin (attinēre, from ad- "to" + tenēre "to hold") meaning "to reach, achieve." able: a suffix of latin origin (-ābilis) via old french, meaning "capable of, fit for."