"scientific study of birds' nests," 1875, from Greek kalia "a dwelling, hut, nest" (from PIE root *kel- (1) "to cover, conceal, save") + -ology. Related: Caliological.
calif
California
caliginous
caligraphy
Caligula
caliology
caliper
caliph
caliphate
calisthenics
call