Undress, n.
1. A loose, negligent dress; ordinary dress, as distinguished from full dress.
2. (Mil. & Naval)
An authorized habitual dress of officers and soldiers, but not full-dress uniform. Undress parade (Mil.), a substitute for dress parade, allowed in bad weather, the companies forming without arms, and the ceremony being shortened.
1 other Webster entry under this spelling
Undress, v. t.
1. To divest of clothes; to strip.
2. To divest of ornaments to disrobe.
3. (Med.)
To take the dressing, or covering, from; as, to undress a wound.
Shades of meaning
Fernald lists undress only as an antonym, under dress.
He lists it without comment; the entries above explain its neighbors.
Synonyms
none given