Real Dictionary

apply
If something such as a rule or a remark applies to a person or in a situation, it is relevant to the person or the situation.
verb: A name that is applied to someone or something is used to refer to them.
verb: If you apply for something such as a job or membership of an organization, you write a letter or email, or fill in a form in order to ask formally for it.
verb: If you apply something such as a rule, system, or skill, you use it in a situation or activity.
verb: If you apply yourself to something or apply your mind to something, you concentrate hard on doing it or on thinking about it.

apply in American English
to put on or spread on; place so as to be touching
intransitive verb: to be pertinent, suitable, or relevant
transitive verb: to make use of as relevant, suitable, or pertinent

apply in British English
verb: to put to practical use; utilize; employ