Definition of physa
1 a
capitalized
:a widely distributed genus (the type of the family Physidae) of freshwater air-breathing snails, having a sinistral, ovate, usually rather short-spired shell and slender nonretractile tentacles with the eyes at their bases
b
plural -s
:any snail of the genus Physa
2
plural physae\-ˌsē, -ˌsī\
also physas
:the lower often retractile part of the body of some anthozoans
