atheism

(narrowly) Belief that no deities exist (sometimes including rejection of other religious beliefs).

(broadly) Rejection of belief that any deities exist (with or without a belief that no deities exist).

(very broadly) Absence of belief that any deities exist (including absence of the concept of deities).

Absence of belief in a particular deity, pantheon, or religious doctrine (notwithstanding belief in other deities).