Invocation or act that seeks to activate a rapport with a deity
Prayer is an invocation or act that seeks to activate a rapport with an object of worship through deliberate communication. In the narrow sense, the term refers to an act of supplication or intercession directed towards a deity or a deified ancestor. More generally, prayer can also have the purpose of thanksgiving or praise, and in comparative religion is closely associated with more abstract forms of meditation and with charms or spells. Prayer can take a variety of forms: it can be part of a set liturgy or ritual, and it can be performed alone or in groups.
https://en.wikipedia.org/wiki/Prayer