Wiktionary
cavitand
n. (context chemistry English) any of several classes of macrocycle that have a shape containing a cavity in which a guest molecule or ion may fit
Wikipedia
Cavitand
A cavitand is a container shaped molecule. The cavity of the cavitand allows it to engage in host-guest chemistry with guest molecules of a complementary shape and size. Examples include cyclodextrins, calixarenes, pillararenes and cucurbiturils.