'distention' originates from Latin, specifically the word 'distentio', from the verb 'distendere', where the prefix 'dis-' meant 'apart' and 'tendere' meant 'to stretch'.

'distentio' (Latin) passed into Medieval Latin and Late Latin as 'distensio'/'distentio', influenced by Old French forms and later English borrowing, yielding modern English 'distention' (with variant spelling 'distension').

Initially it meant 'a stretching apart' or 'the act of stretching'; over time the sense shifted toward 'swelling' or 'expansion' (especially in medical contexts) and retained that specialized meaning.