Ex nihilo is a Latin phrase meaning "out of nothing". It often appears in conjunction with the concept of creation, as in creatio ex nihilo, meaning "creation out of nothing"—chiefly in philosophical or theological contexts, but also occurs in other fields.
In theology, the common phrase creatio ex nihilo ("creation out of nothing"), contrasts with creatio ex materia (creation out of some pre-existent, eternal matter) and with creatio ex deo (creation out of the being of God).
The phrase ex nihilo also appears in the classical philosophical formulation ex nihilo nihil fit, which means "Out of nothing comes nothing".
Ex nihilo when used outside of religious or metaphysical contexts, also refers to something coming from nothing. For example, in a conversation, one might raise a topic "ex nihilo" if it bears no relation to the previous topic of discussion. The term has specific meanings in military and computer science contexts.
In mathematics, ex nihilo can refer to an answer to a question provided with no working, thus appearing to have developed "out of nothing".