Learner's definition of USAGE
1 a : the act of using something
b : the way that something is used c : the amount of something that is used d : how often something is used
Seat belt usage in the state is now mandatory.
Usage [=use] of this exit is prohibited.
drug usage among college students
2 : the way that words and phrases are used in a language
This word occurs in casual/common/popular usage.
differences between British and American usage
a usage manual/guide/dictionary