1) a person who has a share in the profits of a business etc in addition to her or his salary or wages (co-partner)
2) (an instance of) wanting to know or learn (more) about a person or thing; the money charged or paid for borrowing; a legal right to share in a business etc, especially in its profits (interest)
3) to share in something (partake)
to work or act together in order to bring about a result
aid, assist