constrictor

noun4

1. •
   That which constricts or tightens.
2. •
   Ellipsis of boa constrictor, either the species Boa constrictor or a similar snake that kills by constriction.
3. •
   A muscle whose contraction narrows a vessel or passage or compresses an organ.
4. •
   Ellipsis of pharyngeal constrictor (“each of the muscles which constrict the pharynx”).