A person who shares or is associated with another in some action or endeavor; sharer; associate. She is my partner in the new business venture.
Either of two people who dance together. He was my partner for the tango competition.
A spouse or romantic companion. He introduced his partner to his family at the reunion.
A member of a partnership, especially in a business. As a partner in the law firm, she has a say in major decisions.
One of two people playing on the same side in a game or sport. My tennis partner and I won the doubles match.