'diastereoisomer' originates from Modern scientific coinage (ultimately from Greek and New Latin), specifically the combination of the Greek prefixed element 'dia-' (from Greek 'διά') meaning 'apart' or 'through' and the element 'stereoisomer' (from Greek 'stereos' meaning 'solid' and New Latin/Greek 'isomer' from 'isómeros' meaning 'equal part').

'diastereoisomer' developed in modern chemistry by combining 'dia-' with 'stereoisomer' (and is closely related to the variant 'diastereomer'); the term emerged in the late 19th to early 20th century as stereochemistry concepts were formalized and entered English scientific usage.

Initially coined to describe stereoisomers that are not mirror images (distinct from enantiomers), the term has retained this technical meaning in modern organic and stereochemical contexts.