Mahjong glossary

The words you'll meet across mahjong styles and mahjong AI, in plain English.

Tiles and hands

Suit

The three numbered groups of tiles, 1 to 9: characters (also called craks or wan), dots (circles, pin) and bamboo (bams, sou).

Honour tiles

The winds (East, South, West, North) and dragons (red, green, white). They can't form sequences.

Terminal

A 1 or a 9 of any suit.

Flower

Eight extra tiles. In Hong Kong and Taiwanese mahjong they're bonus tiles, set aside and replaced; in American mahjong they're used in the hands on the card; in Indian Mahjong flowers and seasons act as jokers. Riichi doesn't use them.

Joker

A wild tile. American mahjong has 8, usable only in groups of three or more. American mahjong jokers.

Red five

In Riichi, a five printed in red that counts as dora.

Wall

The stacked tiles players draw from. The dead wall is a reserved section used for replacement draws and, in Riichi, dora indicators.

Sets and calls

Pung / pon

Three identical tiles.

Chow / chi

Three consecutive tiles of one suit, like 4-5-6. Only the next player in turn can claim a discard to make one. American mahjong doesn't use chows.

Kong / kan

Four identical tiles. In Riichi, Hong Kong and Taiwanese mahjong, declaring one earns a replacement draw.

Quint

Five identical tiles, possible only with jokers in American mahjong.

Pair

Two identical tiles; most winning hands need exactly one.

Exposed / open

A set made by claiming a discard, laid face up. Opening your hand can cost scoring patterns that need a concealed hand.

Concealed / closed

A hand with no claimed sets.

Winning

Mahjong

Declaring a complete winning hand.

Ron

Winning on another player's discard (Riichi term).

Tsumo / self-draw

Winning with a tile you drew yourself.

Tenpai / ready

One tile away from a winning hand. In Indian Mahjong this is declared as Fishing.

Shanten

How many tiles a hand is from tenpai. Engines use it to measure progress.

Wait

The tile or tiles that would complete your hand.

Chicken hand

A winning hand with almost no scoring value. Some rule sets set a minimum hand value to rule out cheap wins; the LRC Taiwanese sheet gives a near-empty hand a fixed Chicken Hand score.

Riichi terms

Riichi

Declaring tenpai with a closed hand and betting 1,000 points. Your hand is then locked. How to play Riichi.

Yaku

A scoring pattern. Every Riichi win needs at least one.

Han

Units of hand value from yaku and dora.

Fu

Points from how a hand is built and won; combined with han to set the payment.

Dora

Bonus tiles revealed by an indicator. They add han but are not a yaku.

Ura dora

Hidden dora revealed after a riichi win, counted only for the riichi winner.

Furiten

You can't win by ron on a tile that's in your own discards. Self-draw is still allowed.

Hanchan

A full Riichi match of an East round and a South round.

Sanma

Three-player Riichi. Sanma rules.

Other styles

Charleston

The tile-passing ritual before American mahjong hands. The Charleston, explained.

NMJL card

The yearly card from the National Mah Jongg League listing every legal American hand and its value.

Joker exchange

Swapping the real tile for a joker in another player's exposure on your turn (American).

Faan

Doubling units in Hong Kong scoring.

Tai

Scoring units in many Taiwanese tables.

Mixed Chow and Crochet

Melds unique to Indian Mahjong: a run across three suits, and one tile of each suit at the same rank.

Engines and ratings

Dan

Rank on a ladder such as Tenhou's. On Tenhou, 10 dan is the highest regular rank, reached by few humans and a handful of AIs.

Stable rank

The rank a player's placement rates would settle at over many games. Fairer than peak rank, which a lucky run can inflate.

Duplicate match

Engines play the same tile sequences from every seat to cancel out luck.

Policy

An engine's probabilities for each possible move, like the bars on our homepage hand.

mjai

A JSON protocol that lets Riichi engines and game servers talk to each other.

Reinforcement learning

Training an AI by having it play and learn from results, as Suphx and Mortal do.