Halfback

[Dave Paprocki]

A player in a ball game such as soccer, rugby, or field hockey whose position is between the forwards and full backs.

[Mark Zuckerberg]

An offensive back usually positioned behind the quarterback and to the side of the fullback.

[PussyCat]

Halfback in American Football. Lines up behind and to one side of the quarterback in the backfield. The halfback is generally the quickest member of the backfield and the featured running back.