The word 'unemotional' is a modern English formation built upon the noun 'emotion', which entered the language in the 16th century from French émotion, itself derived from Latin emovere ('to move out, stir up'). The Latin root is a combination of e- ('out') and movere ('to move'), tracing back to the Proto-Indo-European root meue- ('to push away'). The prefix un-, of Old English origin, is added to negate the base word, while the suffix -al converts the noun into an adjective. Thus, the literal construction "not pertaining to a stirring out [of feelings]" logically evolved to describe a person who does not exhibit outward feelings or passion.

Structure: un (not) + emotion (feeling) + al (adjective suffix) - un: a prefix of Germanic origin, meaning "not" or "the opposite of". - emotion: a noun of French and Latin origin, from Latin emotio (a moving, agitation), from emovere (to move out, stir up). - al: an adjective-forming suffix of Latin origin, via French -el or -al.