The word "after" is a preposition and adverb that indicates something following in time, place, or order. It is used to denote a point in time that comes subsequent to another event or action. For example, if you say "I will eat after school," it means that you will eat at a time that follows the end of your school day.
The word "after" originates from Old English "æfter," which means "after, behind, or according to." It has Germanic roots, connecting to similar words in other Germanic languages.