chop blockn. Football An illegal block of an opposing player below the knees, called when the block comes from the side or behind or when the player being blocked is already engaged with an opponent.[chop + block.]American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.