The term 'SAY 'I Do'' is a phrase commonly used in wedding ceremonies when the couple is asked if they take each other as husband and wife. The crossword solutions for this phrase are UNITE (5 letters) and WED (3 letters). UNITE is a verb meaning to join together or combine, while WED is a verb meaning to marry. Therefore, the phrase 'SAY 'I Do'' is a combination of the two words UNITE and WED, which together signify the act of marriage.