Ooyamaneko.net

Concealed
A group is concealed if it is made by using only self-drawn tiles.

Tenpai
A player's hand is tenpai if it fulfils all these conditions:
1) The hand's 13 tiles needs only one more tile to form a complete hand of four groups and a pair, or seven different pairs, or the Thirteen Orphans yaku.
2) The completing tile must exist, even if it's not available.
A hand needing five identical tiles can never be completed, so it is not tenpai.
It does not matter if all completing tiles have been discarded, or are locked in other payer's hands, or are in the dead wall. Only the hand's 13 tiles are considered to determine if the hand is tenpai or noten.
3) The player is not under a "dead hand" penalty.

During the player's turn, the hand's 14 tiles is tenpai if it will fulfil the above conditions after discarding.

Noten
A hand is noten if it is not tenpai.

Winning hand
A player's hand is a winning hand if it fulfils all these conditions:
1) It has four groups and a pair, or seven different pairs, or the Thirteen Orphans yaku.
2) It has at least one yaku.

Closed
A hand is closed if it is made by using only self-drawn tiles, beside the winning tile.
If the hand is completed by calling a tile (ron), the last group or pair is melded but the hand is still closed.

Yaku
A yaku is a scoring pattern.
Each yaku gives one or more han.

Dora
Each dora gives one han.

Han
One of the two scoring units used for evaluating the hand.
Earned from yaku and dora.

Minipoints / Fu
One of the two scoring units used for evaluating the hand.
Earned from groups, pairs and winning event.

Hanchan (sometimes called Session)
East and South rounds.

Hanchan score
After each hanchan, the "hanchan score" is calculated as follow, without rounding:
(points - 30,000) / 1,000 + uma