Mahjong Glossary: Tenpai, Shanten, Waits, Tile Efficiency, and More

Riichi mahjong and "what would you discard" (nanikiru) problems are full of terms like tenpai, shanten, ukeire, and ryanmen. Once you know what they mean, problems and commentary become far easier to follow, so here is a glossary of the words that come up most often. Browse to whatever term you need; each topic is explored in depth in the related columns at the bottom of the page.

Tenpai (ready) / Noten

Tenpai means your hand is just one useful tile away from a win — complete except for the final tile. Noten means you are not tenpai. Most "what to discard" (nanikiru) problems ask how to reach tenpai as fast as possible.

Shanten

How many useful tile-swaps away from tenpai your hand is. Tenpai = 0-shanten; one step before that = 1-shanten. A core rule of efficiency is never to move backward (raise your shanten).

Win (agari / hora)

Completing your hand — four sets and one pair — by drawing the winning tile yourself (tsumo) or claiming an opponent's discard (ron), and scoring. The goal of the game.

Acceptance (ukeire)

The kinds and number of tiles that, when drawn, advance your shanten (bring you closer to tenpai). Tile-efficiency problems are about choosing the discard that maximizes ukeire.

Tile efficiency (haikoritsu)

The way of thinking that maximizes acceptance to reach tenpai and the win as quickly as possible. When in doubt, keep the shape with the wider acceptance.

Wait shapes (ryanmen / kanchan / penchan / shanpon / tanki)

The shape of the tiles you wait on at tenpai has a name. Ryanmen (two-sided wait) = two consecutive tiles (e.g., 3-4) waiting on both ends (2 and 5) — the most tiles, and the best wait. Kanchan (closed wait) = a gap shape (e.g., 3-5) waiting on the middle tile (4). Penchan (edge wait) = an edge shape (1-2 or 8-9) waiting on one side only (3 or 7). Shanpon (dual-pair wait) = two pairs (e.g., 3-3 and 5-5) waiting for either to become a triplet. Tanki (pair wait) = a single tile waiting for its partner to complete the pair. Efficient play keeps shapes that can settle into the wider ryanmen.

Pair (atama / jantou)

Two identical tiles — the "head" that a winning hand needs exactly one of, kept separate from the four sets.

Set / meld (mentsu)

A group of three tiles — a sequence (shuntsu, three in a row like 1-2-3) or a triplet (kotsu, three of a kind like 3-3-3). A winning hand is four sets plus one pair (14 tiles).

Partial set (taatsu)

A two-tile shape that is one tile short of a set (a ryanmen, kanchan, penchan, or pair). Building a hand means turning partial sets into complete sets.

Floating / isolated tile (ukihai / koritsuhai)

A lone tile not part of any set or partial set. Because it does not directly help complete the hand, it is the prime candidate to discard in nanikiru (though future potential and safety matter too).

Dora

A bonus tile that raises your score when you win while holding it. Balancing the value of keeping dora against hand speed (efficiency) often decides a nanikiru choice.

Yaku

A required scoring condition for a win (riichi, tanyao, pinfu, and so on). As a rule you cannot win with no yaku at all. Calling removes concealed-only (menzen) yaku such as riichi, but many yaku — tanyao, yakuhai, honitsu, and others — still work when you call.

Riichi

The most basic yaku, declared when you reach tenpai while concealed (no calls). You bet 1,000 points and gain scoring potential, but you can no longer change your hand after declaring.

Calling — open melds (naki / furo: pon, chii, kan)

Making a set from another player's discard. Pon = a triplet, chii = a sequence (only from the player to your left), kan = four of a kind. Calling speeds up your hand but breaks concealment, so concealed-only yaku like riichi become unavailable (tanyao, yakuhai, and other call-friendly yaku still work).

Safe tile (anzenpai / anpai)

A tile that cannot deal in (be ronned) to an opponent. A tile that an opponent has already discarded (genbutsu) is 100% safe against that player and is the staple of folding.

Suji

A defensive read that rules out two-sided (ryanmen) waits from a riichi player's discards. For example, if 4 has passed safely, the ryanmen shapes that include 4 (1-4 and 4-7) are impossible, so 1 and 7 are relatively safe (suji).

Wall / no-chance (kabe)

A defensive clue: when all four copies of a tile are visible, a wait using that tile cannot exist. For example, if all four 8s are visible, the ryanmen 6-7 (waiting on 5-8) is impossible, so 5 is relatively safe.

Push/fold (oshihiki) / betaori

Push/fold is deciding whether to attack (push) or give up (fold) by weighing your hand's value (speed and points) against the opponent's threat (such as a riichi). Betaori is folding completely — abandoning the win and discarding only safe tiles to avoid dealing in.