Definition of “spare” - Learner’s Dictionary

spare

adjective uk us /speər/

B1 If something is spare, it is available to use, because it is extra and not being used:

a spare bedroom
spare cash
spare parts
spare time

A2 time when you are not working:

I enjoy gardening in my spare time.

(Definition of “spare adjective” from the Cambridge Learner's Dictionary © Cambridge University Press)