1) Having a low-cut neckline 2) Low-cut 3) Low-necked 4) Necked 5) Wearing a low-necked garment 1) Necked 
• (a.) Leaving the neck and shoulders uncovered; cut low in the neck, or low-necked, as a dress. • (a.) Wearing a decollete gown.
Dé`col`le·té' (da`kŏl`l e *ta') adjective Wearing a décolleté gown. Dé`col`le·té' adjective [ French, past participle of décolleter to bare the neck and shoulders; dé- + collet collar, from Latin collum neck.] Leaving the neck and shoulders uncovered; cut low in the neck, or low-necked, as a dress. 
[adj] - (of a garment) having a low-cut neckline
low-cut adjective (of a garment) having a low-cut neckline; `a low neckline`