WordWeb Online

1. (sport) illegally beyond a prescribed line or area or ahead of the ball or puck
   "the touchdown was nullified because the left tackle was offside";
   - offsides

1. (sport) the mistake of occupying an illegal position on the playing field (in football, soccer, ice hockey, field hockey, etc.)

1. Illegally in advance of the ball or puck

Derived forms: offsides

Type of: error, fault, mistake

Encyclopedia: Offside