'troglodytic' originates from Greek, specifically the word 'troglodytēs', where 'troglē' meant 'cave' and the element '-dytēs' indicated 'one who enters or dwells'.

'troglodytēs' passed into Late Latin as 'troglodyta' and then into Middle English as 'troglodyte'; the adjective 'troglodytic' was later formed in English to describe things relating to troglodytes.

Initially it meant 'cave-dweller', but over time it also came to be used figuratively to mean 'reclusive, primitive, or brutish', and this broader sense is common in modern usage.