The soul – in many traditional spiritual, philosophical, and psychological traditions – is the incorporeal (and immortal) essence of a person, living thing, or object. Some belief systems (including the Abrahamic religions) argue that only human beings have souls and therefore that among the biological organisms of the Earth only they possess immortality and the possibility of union with the divine. In contrast others (such as Jains) believe that all biological organisms have souls, and others further still that even non-biological entities (such as rivers and mountains) possess souls. This latter belief is called animism.

Soul can function as a synonym for spirit, mind or self; scientific works, in particular, often consider 'soul' as a synonym for 'mind'.