The word "before" is a preposition and adverb that indicates a time or event that occurs earlier than a specified point in time or another event. It can refer to actions or occurrences that take place prior to something else. For example, if you complete your homework before dinner, it means that the homework is finished earlier than the time you eat dinner.
The word "before" comes from the Old English "beforan," which means "in front of, previously." It is made up of the prefix "be-" meaning 'by' or 'near,' and "foran," which means 'in front' or 'before.'