'low-neck' is a modern English compound formed from 'low' + 'neck', where 'low' means 'not high' and 'neck' refers to the neckline or upper part of the torso.

'low-neck' arose as a descriptive compound in Modern English (late 19th to 20th century) from combining the adjective 'low' and the noun 'neck' (as in 'neckline'), producing forms like 'low-necked' and the noun usage 'low-neck'.

Initially a straightforward compound meaning 'neck (or neckline) that is low', it has remained largely descriptive and is used chiefly to describe styles of clothing (sometimes informally shortened to refer to the garment).