Definition of “season” - Learner’s Dictionary

season

noun [ C ] uk us /ˈsiːzən/
PART OF YEAR

B1 one of the four periods of the year; winter, spring, summer, or autumn

SPECIAL TIME

B1 a period of the year when a particular thing happens:

the rainy/dry season
the football season
in season

B2 If vegetables or fruit are in season, they are available and ready to eat.

If a female animal is in season, she is ready to mate.

out of season

If vegetables or fruit are out of season, they are not usually available at that time.

If you go somewhere out of season, you go during a period of the year when few people are there.

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