Onside Kick?

[Robert Goodman]

It's a term that's never appeared in the rule book, with two exceptions noted below, but was coaching shorthand to refer to the recovery of the ball by an onside player as explained by MD Longhorn upthread. The usage makes no sense when applied to free kicks as today, because if there are offside players of team K, the play's not going to stand up anyway. The term was most useful as applied to recovery by onside players of kicks during general play, as is still legal in Canadian football. In Canadian football rule books, there is one use of the phrase regarding responsibility of officials in "`onside kick' situations", recognizing it as a kind of coaching shorthand that officials would be expected to understand, even though not defined in the rule book.

Similarly, when, fairly recently, the NFL adopted different penalties for free kicks out of bounds under different circumstances, they differentiated between other kicks and an "onside kick", which appears to be implicitly defined (though I'm not sure it is) as one that doesn't go at any time more than 20 yards beyond the previous spot.