1. （人体内、尤指鼻内生长的）息肉
A polyp is a small unhealthy growth on a surface inside your body, especially inside your nose.

2. 水螅（体）
A polyp is a small animal that lives in the sea. It has a hollow body like a tube and long parts called tentacles around its mouth.

1. one of two forms that coelenterates take (e.g. a hydra or coral): usually sedentary with a hollow cylindrical body usually with a ring of tentacles around the mouth

e.g. in some species of coelenterate, polyps are a phase in the life cycle that alternates with a medusoid phase

2. a small vascular growth on the surface of a mucous membrane

Synonym: polypus