- The definition of onside is in a position to play.
An example of onside used as an adjective is the phrase an "onside position" which means a player is in a spot to get the ball.
- Onside is defined as a sports term that means in the proper position to play.
An example of onside used as an adverb is the phrase an "onside move" which means a move that allows the player to get the ball.
onside definition by Webster's New World
onside definition by American Heritage Dictionary
adverb & adj. Sports