noun, used as a suffix, noun
Refers to a rival, opponent, or enemy, especially one with longstanding enmity. When used as a suffix, it is often pronounced がたき (e.g., 商売敵 しょうばいがたき 'business rival').
彼は私の商売敵だ。
He is my business rival.
宿敵との戦いに勝った。
We won the battle against our longtime enemy.
noun
Used in set phrases like 敵を討つ (かたきをうつ) 'to avenge someone' or 敵討ち (かたきうち) 'revenge'.
父の敵を討つために旅に出た。
He set out on a journey to avenge his father.
noun
Archaic usage meaning 'spouse'. Not used in modern Japanese.
古文では「敵」が配偶者を指すことがある。
In classical literature, 敵 can refer to a spouse.