back is one of the most commonly used words in English with multiple meanings:
1. As a noun: the rear surface of the human body from the shoulders to the hips
2. As a verb: to support or give financial help to someone or something
3. As an adverb: in return or in reply
4. In sports: a player positioned behind the front line
5. In computing: to return to a previous screen or page
6. In finance: to provide financial support for a project