'parallelogram' originates from French 'parallélogramme' and ultimately from Greek 'parallēlogrammon', where 'parallēlos' meant 'beside one another' (from 'para-' meaning 'beside' + 'allēlos' meaning 'each other') and 'gramma' meant 'something written or drawn (a line)'.

'parallēlogrammon' (Greek) → Neo-Latin/French 'parallelogramma' / 'parallélogramme' → English 'parallelogram' (late 16th to 17th century).

Initially it referred to a figure defined by parallel lines and drawn lines; over time it came to mean specifically 'a four-sided figure whose opposite sides are parallel,' which is the current mathematical meaning.