1) Aisle attendant 2) Attendant 3) Attender 4) Tender 5) Wedding attendant 6) Wedding ceremony participant 1) Usher 
In North America, a groomsman is one of the male attendants to the groom in a wedding ceremony. In Britain, a similar role is performed by an `usher`. Usually, the groom selects close friends and relatives to serve as groomsmen, and it is considered an honor to be selected. From his groomsmen, the groom usually chooses one to serve as best man. .....
• (n.) A male attendant of a bridegroom at his wedding; -- the correlative of bridesmaid.
Grooms'man noun ; plural Groomsmen A male attendant of a bridegroom at his wedding; -- the correlative of bridesmaid. 
[n] - a male attendant of the bridegroom at a wedding
These are members of the groom’s party and officially attend to the groom at a wedding.