'parenthesis' originates from Greek, specifically the word 'parenthesis' (παρένθεσις), where 'para-' meant 'beside' and 'entithenai' meant 'to put in'.

'parenthesis' changed from Greek 'parenthesis' into Late Latin 'parenthesis', passed into Old French/Anglo-Norman, and eventually entered Middle English as 'parenthesis'.

Initially, it meant 'an insertion' or 'a placing beside', and over time it came to refer specifically to both the inserted remark and the punctuation marks used to set such insertions off.