I do this for a living. Seasonality as a generic term refers to temporally periodic signals but can even be extended to talk about non-temporal aspects of a signal. The same math used in areas like econometrics to remove periodicity in annual data can be applied to multiple domains. The main motivation to removing or isolating periodicity is to allow for investigation into the underlying phenomena, or to allow the investigation of the sources of periodicity independently of other drivers. In every case, though, seasonality is an acceptable term in everything I’ve written, read, and worked on.