The term 'One of a Couple' can be represented by three different crossword solutions: MATE (4 letters), MRS (3 letters), and PARTNER (7 letters). MATE is a term used to refer to a close friend or companion, while MRS is an abbreviation for the title of a married woman. Finally, PARTNER is a word used to describe someone who is in a romantic relationship with another person. All three words are used to describe someone who is part of a couple.