1.
reserve; spare
Something kept in case of need; a backup or extra supply.
Compounds
- 予備校 (prep school, cram school for university entrance)
- 予備選挙 (primary election)
- 予備軍 (reserve forces; figuratively, people at risk of becoming something: 糖尿病予備軍, people at risk of diabetes)
- 予備費 (reserve fund)
- 予備知識 (background knowledge)
- 予備日 (backup day, e.g. if an event is rained out)
Common patterns
- 予備の + noun (spare X, reserve X)
- 予備 + noun (preparatory X)