'stereomer' originates from Greek, specifically the elements 'stereos' (meaning 'solid' or 'three-dimensional') and 'meros' (meaning 'part'). In chemistry the combining form 'stereo-' denotes spatial relation, while '-mer' (as in 'isomer') relates to parts or units.

'stereomer' developed as a short form from 'stereoisomer' (coined in the context of stereochemistry in the late 19th and early 20th centuries). 'Isomer' itself comes from Greek 'isos' (equal) + 'meros' (part), and was adapted into chemical usage before 'stereoisomer' and its shortened form emerged.

Initially the elements 'stereos' and 'meros' separately meant 'solid/three-dimensional' and 'part'; in modern chemical usage the combined form 'stereomer' specifically refers to an isomer distinguished by spatial arrangement rather than connectivity.