noun
penchan wait; edge wait
A mahjong term for a one-sided wait on the end tile of a run, e.g. waiting for a 3 when holding 1-2, or a 7 when holding 8-9. This is a specific type of ryanmen-machi (two-sided wait) that only completes one side of a sequence.
辺張待ちでリーチをかけたが、最後まで引けなかった。
I declared riichi with a penchan wait, but I couldn't draw the winning tile until the end.
この手は辺張待ちだから、待ち牌は一種類だけだ。
This hand has a penchan wait, so there's only one type of tile I'm waiting for.
A two-sided wait that completes a sequence on either end, e.g. waiting for 3 or 6 with a 4-5 shape. 辺張待ち is a one-sided wait on the end of a run, making it weaker than 両面待ち.
A closed wait (kanchan) that completes a sequence in the middle, e.g. waiting for a 4 with a 3-5 shape. 辺張待ち waits on the edge, while 嵌張待ち waits on the middle tile.
From Chinese mahjong terminology: 辺 (pen, 'edge') + 張 (chan, 'stretch/extend') + 待ち (machi, 'wait'). The term describes a wait that stretches to the edge of a sequence.