loose head 
noun Rugby
The forward in the front row of a scrummage who is nearest to the scrum half as the ball is put in.Immediately after the restart, Stockport approached the referee to inform him that their loose head prop could not continue, and the replacement was not an experienced front row forward....
- Returning from injury, the loose head set the move in motion then reappeared on the wing to take a scoring pass and dive over for a fine score.
- He is so tall that opposite loose heads can get under him and put him in trouble.