Enemy
Opponent
noun
The kanji and the word are exactly the same. That means they share meanings as well.
敵 means enemy or opponent, whether in war, sports, competitions, or other conflict situations. Just keep in mind that 敵 can sound a bit strong!
The main reading is the same one you learned with the kanji. But there's also a secondary かたき reading you haven't seen yet, so here's a mnemonic for that:
You love to call your enemy's car tacky (かたき). They're always driving around in some tacky sports car, you can't stand it. Every time they drive by you shout, "Your car is tacky, enemy!"
Note: In terms of differences, the てき reading just means "enemy," whereas かたき typically refers to someone you hold a deep grudge against, often on behalf of another.
「フグ、あなたはどっちの味方なの？私の敵なの？」「僕は君の味方だよ、サーモン。」
"Which side are you on, Fugu? Are you my enemy?" "I’m on your side, Salmon."
ビエトは自分だけの判断で、敵のアジトに向かった。
Viet took matters into his own hands and headed to the enemy's hideout.
いつかアイツに、親の敵を討ちたいんです。
I wish to exact revenge on that person for the sake of my parents someday.