also: cut · chop block (different thing, see below) · low block
Blocking a defender at or below the thigh to put him on the ground. Legal in some situations and at some levels and not others, which is the reason to look it up.
2 meanings, all below. Jump to the one you heard.
The blocker attacks a defender low, at or around the thighs, aiming to put him on the ground rather than to drive him anywhere. Against a bigger or faster defender it can be effective where nothing else is, which is exactly why it is regulated.
A defender on the ground cannot pursue, so a cut block does not have to be sustained the way an upright block does. That is its appeal and, from the defensive side, the reason it is resented.
low blockchop blockThis is the sense most coaches are actually looking for. What is permitted differs between youth, high school, college and professional football, and within a level it usually depends on where the block happens and whether the defender is already engaged.
One distinction is worth carrying regardless: a cut block is one blocker going low, while a chop block is one blocker engaging a defender high while another goes at him low. Those are treated as different acts and the second is far more serious. **The specific rules are not stated here because they have not been checked against a current rulebook, and a wrong legality claim is the most damaging kind of error this glossary can make.** Check your own level's rulebook and your league's local modifications, which frequently differ from the governing body's default at youth level.
chop blockYouth leagues commonly restrict low blocking further than the governing body they otherwise follow, and those local modifications are the version that governs your Saturday. Do not assume the high school rulebook applies to a youth league that says it uses high school rules.