low neckline
plunging neckline

The low neckline of the dress could be filled with a partlet.

Did Carolan think her black velvet could do with a slightly lower neckline?

His lips moved lower, trailing along the low neckline of her gown as he talked.

He gazed at the low neckline of her straining sweater.

She had never worn such a low neckline in her life, much less even lower.

Not all, not more than a really low neckline would show, but it was distracting him.

This would allow you to wear clothing with a lower neckline and still keep the scar covered.

Though pressure from the press intensified, she revealed nothing about the dress except that it was white and had a low neckline.

The suggestion of nipples showed at the woman's low neckline.