Meaning

verb to come or go into

verb become a participant; be involved in

verb register formally as a participant or member

originFrom Middle English entren, from Old French entrer, from Latin intrō (“enter”, verb), from intrā (“inside”). Has been spelled as "enter" for several centuries even in the United Kingdom, although British English and the English of many Commonwealth Countries (e.g. Australia, Canada) retain the "re" ending for many words such as centre, fibre, spectre, theatre, calibre, sombre, lustre, and litre.

Etymology from Wiktionary, CC BY-SA 3.0