Tighthead scrum

Question
What exactly does it mean when a team has lost or been penalised a "tighthead scrum"?

Answer
To loose a tighthead scrum means you had the feed and your team was beaten in the scrum. The opposition won it back. A scrum is a restart of play and if you are awarded the feed you are technically at an advantage. So if your guys are out powered or their hooker is quicker and win the ball back "against the head" because on your put in the ball goes under their tighthead prop and your loosehead thus creating your advantage.

I am not sure what you mean by being penalized a tighthead scrum, that sounds like you might have miss heard the call.