The word 牌局 is formed by combining the character 牌 (pái), which means "card" or "tile" as used in games, with the character 局 (jú), which means "game" or "session". Together, they create a compound term where 牌 specifies the object involved, and 局 denotes the organized activity, resulting in a word that refers specifically to a card game session or a gaming round like mahjong.