'decolletage' originates from French, specifically the word 'décolletage', where 'dé-' meant 'off' or 'un-' and 'collet' (from Old French) related to 'neck'.

'decolletage' entered English from French 'décolletage' (19th century), which derived from French 'décolleté' (past participle of 'décolleter' / 'décolletter'), and ultimately from Latin root 'collum' meaning 'neck'.

Initially, it referred to the action or result of 'décolleting' (exposing the neck), but over time it came to mean specifically the low neckline or the area of the upper chest that is exposed.