Jantou
Jantou「雀」 means the pair in the winning hand. Every winning hand, with the exception of seven pairs, has one jantou. Even the irregular yakuman kokushi musou requires jantou.
Fu
Certain tile pairs produces fu. Each produces 2 fu.
Tanki
Only one wait pattern involves the pair directly: tanki. It is conveniently known in English as the "pair wait". This pattern only arises, when the hand contains four complete tile groups.