Productive prefix attached to nouns, often loanwords, to mean 'before' or 'preliminary'. Common in compounds like プレテスト (pre-test) or プレオープン (pre-opening).
A pre-launch event for the new product was held.
Check the team's condition in pre-season games.
The pre-sale starts next week.
Borrowed from English 'pre-', used as a prefix in Japanese mainly with loanwords.