Definitions for "Best man"
This guy acts as groom's valet (personal aide and advisor) through all stages of wedding planning. He's a fashion consultant, bachelor-party master of ceremonies, and commander-in-chief of the groomsmen brigade. His duties include (but aren't limited to): getting the groom to the ceremony on time; giving the officiant his/her fee after the ceremony; signing the couple's marriage license; and holding the bride's ring at the altar. He also is famous for his toasting skills and dancing savoir faire.
The best man will have numerous duties; keeping the ring safe, sign the marriage license, announcing speeches at the reception and making his own.
the principal groomsman at a wedding