低领口

low-cut neckline

low / beneath / to lower (one's head) / to let droop / to hang down / to incline

neck / collar / to lead / to receive / classifier for clothes, mats, screens etc

collar / neckband / neckline / the place where the two ends of a collar meet

mouth / classifier for things with mouths (people, domestic animals, cannons, wells etc) / classifier for bites or mouthfuls