ˈkaktəs noun
Etymology: New Latin, from Latin, cardoon, from Greek kaktos
1. capitalized , in some classifications : a genus of globose spiny plants (family Cactaceae) now referred to several other genera (as Melocactus and Coryphantha )
2. plural cac·ti -ˌtī, -(ˌ)tē or cactuses -_təsə̇z : any plant of the family Cactaceae — see carnegiea , echinocactus , mescal , opuntia