n. 1. That which constricts, draws together, or contracts. [ 1913 Webster ]
2. (Anat.) A muscle which contracts or closes an orifice, or which compresses an organ; a sphincter. [ 1913 Webster ]
3. (Zool.) A serpent that kills its prey by inclosing and crushing it with its folds; as, the boa constrictor. [ 1913 Webster ]