'anti-optimism' originates from Greek and English: specifically the prefix 'anti-' (from Greek 'antí') and the English noun 'optimism' (from French 'optimisme', ultimately from Latin 'optimus'), where 'anti-' meant 'against' and 'optimus' meant 'best'.

'anti-optimism' was formed in modern English by combining the Greek-derived prefix 'anti-' with the established English word 'optimism'. 'Optimism' entered English via French 'optimisme' from Latin 'optimus' ('best'); the compound construction follows a long pattern of English formations using Greek/Latin prefixes.

Initially, 'optimism' referred to the philosophical doctrine (e.g., Leibniz's claim that this is the best of all possible worlds); over time it broadened to mean a general positive outlook. 'Anti-optimism' accordingly evolved to denote opposition to that outlook—whether philosophical, cognitive, or rhetorical.