opponent's territory; opponent's side of the field
Used in competitive karuta to refer to the area where the opponent places their cards. A domain-specific term.
相手陣の札を素早く取るのが勝負の鍵だ。
Quickly taking cards from the opponent's territory is the key to winning.
Compound of 相手 (opponent) and 陣 (camp, formation). The exact historical derivation is uncertain, but the term is used in competitive karuta.