ex-boyfriend or ex-girlfriend

(mahjong) big three dragons: a 役満 (yakuman, “limit”) hand with triplets or quads of each of the 三元牌 (sangenpai, “dragon tiles”)

(mahjong) little three dragons: a 役 (yaku, “hand”) with triplets or quads of two of the 三元牌 (sangenpai, “dragon tiles”), plus a pair of the third; worth 2 翻 (han, “doubles”). Because 2 翻 is added from the 役牌 (yakuhai, “meld of seat/prevailing wind or dragon”) of the two dragons, the total is actually 4 翻.

(mahjong) Generic name of the three dragon tiles: 白 (haku, “white dragon”), 發/𤼵 (hatsu, “green dragon”), and 中 (chun, “red dragon”)

(monarchy) an East Asian practice of dating, using exactly one distinct era name for each monarch's reign, where such era name also eventually becomes the monarch's posthumous name

being alicyclic (of a class of organic compounds)

boustrophedon style

tautology (in logic)

(architecture) Synonym of ドーリア式 (Dōria-shiki, “Doric order”)

Synonym of アメリカンフットボール (Amerikan futtobōru, “American football”)