Cuculiformes originated from New Latin: Cuculi meaning cuckoo, formes meaning forms. 
The bird order contains only one family: the cuckoos (Cuculidae).
The family Cuculidae includes bird species such as the common or European cuckoo, roadrunners, koels, malkohas, couas, coucals, and anis.

Formerly the family hoatzin (Opisthocomidae) was included in the order Cuculiformes but is now split to be in a separate order: Opisthocomiformes.