From Longman Dictionary of Contemporary Englishfive-a-sideˌfive-a-ˈside adjective [only before noun] British English five-a-side football is played with five players on each side, usually indoors
Examples from the Corpus
five-a-side• The course includes coaching, training, an Ayresome Park tour, and a five-a-side competition.• Cheshire Constabulary youth five-a-side contest is open to teams of seven, including substitutes, from under-10s to under-16s.• There was a little five-a-side league there.• Robert is a keen footballer, playing for Stoddard's team in the Paisley and District five-a-side league.• From Easter onwards, the area is laid with eight tennis courts and three five-a-side pitches.• He also plays five-a-side soccer three times a week. 