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Scrum
The eight forwards from each team bind together and push against each other. The scrum-half from the team that has been awarded possession feeds the ball into the centre of the scrum from the side most advantageous for his hooker (which is typically the side of loose head prop).
The ball must be fed straight down the middle of the tunnel and the hookers must not contest for the ball until it is put in. If they do, a free-kick is awarded for "foot up".
The scrum is taken again if the ball comes straight out of the tunnel or if it collapses. If the scrum wheels (rotates) due to pushing more than 90 degrees the scrum is reformed and awarded to the other side. Pulling in an attempt to unbalance the other side or to assist in rotating the scrum is a Penalty Offence.
Scrum half
Also known as a half-back, they are the players traditionally wearing shirt number 9. Scrum halves form the all-important link between the forwards and the backs. They are relatively small but with a high degree of vision, the ability to react to situations very quickly, and good handling skills.
They are often the first tackler in defence and are behind every scrum, maul or ruck to get the ball out and maintain movement. They put the ball into the scrum and collect it afterwards. Scrum Halves generally also act as "receiver" in the line-out to catch the ball knocked down by the forwards. (The receiver is a member of the line out and so stands within 10 metres of it and may join the line once the ball is thrown.)
Regularly the toughest non-forward player on the team, they wish that they were big enough to play flanker but aren't quite there.
Set piece
Collective term for the scrum, line-out and sometimes the restart.
Shoeing
At the breakdown a ruck commonly forms over the players involved in the tackle.
Where players who are on the ground on the opposition side of the ruck do not move away quickly enough, players on their feet may be tempted to "help" them move by pushing them away with their boots.
This potentially dangerous act is illegal and if done deliberately (or recklessly) may result in penalties and yellow or red cards.
Short arm penalty
See free kick
Sin bin
The notional area where a player must remain for a minimum of ten minutes after being shown a yellow card. In high level games, the sin bin is monitored by the fourth official.
Sipi Tau
Sipi Tau is a Tongan war dance performed by the Tonga national team before each of their international matches.
Siva Tau
Siva Tau is a Samoan war dance performed by the Samoa national team before each of their international matches.
Spear tackle
A spear tackle is a dangerous tackle in which a player is picked up by the tackler and turned so that they are upside down. The tackler then drops or drives the player into the ground often head,neck or shoulder first.
Spear tackles are particularly dangerous and have caused serious injury including spinal damage, dislocations and broken bones in the shoulder or neck. On rare occasion, even death can occur.
Spear tackles are taken very seriously by the various Union discipline committees and can result in lengthy playing bans.
Stellenbosch Laws
The Stellenbosch Laws were a set of experimental laws of rugby union considered by the International Rugby Board (IRB) from 2006 through 2008. The trials ended in late 2008, with the IRB choosing to adopt roughly half of the proposed changes.
Read more about this topic: Glossary Of Rugby Union Terms