the word 'unperturbed' is formed by adding the common english negative prefix 'un-' to the adjective 'perturbed'. the core, 'perturb', originates from latin 'perturbare', a compound of 'per-' (thoroughly) and 'turbare' (to disturb, agitate), itself from 'turba' (a crowd, tumult). this literal sense of being thoroughly disturbed or thrown into disorder evolved into the modern meaning of being anxious or agitated. therefore, 'unperturbed' logically and directly signifies the state of not being disturbed or agitated, maintaining a calm and composed demeanor.

Structure: un (not) + perturbed (agitated) un- (a prefix of Germanic origin, via Old English, indicating negation or reversal). perturbed (from the past participle of 'perturb', from Latin 'perturbare', meaning to throw into confusion).