Another type of non-stationary process, distinct from those with trends, is a cyclostationary process, which exhibits cyclical variations over time.

Strict stationarity, as defined above, can be too restrictive for many applications. Therefore, other forms of stationarity, such as wide-sense stationarity or th-order stationarity, are often used. The definitions for different kinds of stationarity are not consistent among different authors (see Other terminology).