registration (Noun) — The act of enrolling.
registration (Noun) — The body of people (such as students) who register or enrol at the same time.
registration (Noun) — A document certifying an act of registering.
registration (Noun) — (music) the sound property resulting from a combination of organ stops used to perform a particular piece of music; the technique of selecting and adjusting organ stops.
registration (Noun) — The act of adjusting something to match a standard.