offside

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

(adj) illegally beyond a prescribed line or area or ahead of the ball or puck. Synonyms: offside (vs. onside), offsides. Example: "The touchdown was nullified because the left tackle was offside."

(adv) illegally in advance of the ball or puck.