'atomical' originates from Greek, specifically the word 'atomos', where 'a-' meant 'not' and 'tomos' meant 'to cut (slice)'; the adjective form developed in English via Late Latin/Medieval Latin and Middle English.

'atomical' developed from Greek 'atomos' → Late Latin/Medieval Latin forms such as 'atomicus'/'atomalis' → Middle English 'atomical', eventually yielding the modern English 'atomical'.

Initially, the root referred to 'uncuttable' or 'indivisible' particles; over time the adjective came to mean 'relating to atoms' (and in modern usage is largely replaced by 'atomic').