Longman Dictionary of Contemporary English
Wiktionary
alt. (context rugby union rugby league English) A goal scored by kicking the ball through the goal from open play, after the ball has touched the ground. n. (context rugby union rugby league English) A goal scored by kicking the ball through the goal from open play, after the ball has touched the ground.
Wikipedia
If the drop goal attempt is successful, play stops and the non-scoring team (the scoring team in rugby union sevens) restarts play with a kick from halfway. If the kick is unsuccessful, the offside rules for a kick apply and play continues until a normal stoppage occurs. Because of the scoring attempt this is usually from the kicked ball going dead or into touch. Defenders may tackle the kicker while he is in possession of the ball, or attempt to charge down or block the kick.