ˈfīsə noun
Etymology: New Latin, from Greek physa bellows — more at pustule
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. -s : any snail of the genus Physa
2. plural phy·sae -ˌsē, -ˌsī also physas : the lower often retractile part of the body of some anthozoans