onside kick

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. Football A kickoff in which the ball carries just far enough, at least ten yards, to be recovered legally by the kicking team.

Wiktionary

1. n. alternative spelling of on-side kick.

GNU Webster's 1913

1. (Football) A kickoff in which the kicking team attempts to kick the ball only so far as is legally required (beyond the 50-yard line), so as to have a better chance to recover the kicked ball itself; -- it is a risky type of play used only when the kicking team is losing and there is little time left to play.