special team

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A group of players who play in special situations, such as kickoffs and punt returns, and are usually not involved in most plays from the line of scrimmage.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun American football A group of football players with special assignments for plays other than standard offensive and defensive plays, those involving kicking.
• noun ice hockey A group of ice hockey players most often used during power plays consisting of more defensive players than usual on the team that was penalized in hopes of killing the penalty, or more offensive players than usual on the team with the advantage in players to increase the chance of scoring a goal.