Why is the ninth month called September?
1820, "pertaining to mental conception" (there is an isolated use from 1662), from Medieval Latin conceptualis, from Latin conceptus "a collecting, gathering, conceiving," past participle of concipere (see conceive). Related: Conceptualism; conceptualist.
conceptual con·cep·tu·al (kən-sěp'chōō-əl)
Relating to concepts or the the formation of concepts.