'aphoristical' ultimately derives from Greek via Latin: from Greek 'aphorismos'/'aphorisma' (ἀφόρισμα), where 'apo-' meant 'away, off' and 'horizein' meant 'to limit, define'.

'Aphorismos' passed into Late Latin/Medieval Latin as 'aphorismus' and into Middle English as 'aphorisme' or 'aphorism'; the adjective was formed later with the suffix '-ic'/'-ical' to create 'aphoristic'/'aphoristical'.

Initially it denoted 'a definition or concise statement', and over time it evolved into the modern sense of 'a concise, pithy statement of general truth' and adjectives meaning 'resembling or characteristic of aphorisms'.