'perithecial' originates from New Latin, specifically the word 'perithecium', where the Greek prefix 'peri-' meant 'around' and 'theke' (θείκη) meant 'case' or 'container'.

'perithecial' developed from New Latin 'perithecium' (used in biology for the flask-shaped fruiting body), which in turn derives from Greek 'perithēkē' (περιθήκη); the English adjective formed by adding the adjectival suffix -ial to the New Latin stem.

Initially associated with the literal sense of an 'around-the-case' structure in Greek-derived terms, it evolved to the specific biological meaning 'relating to a perithecium' in modern mycological usage.