「美味しい」 (Oishii) is an i-adjective meaning 'delicious' or 'tasty'. It's used to describe food or drink that has a pleasant flavor and is enjoyable to eat or drink. It's a common and positive way to compliment food.

「美味しい(おいしい)」は「delicious, tasty」という意味(いみ)のい形容詞(けいようし)です。食べ物(たべもの)や飲み物(のみもの)の味(あじ)がいいことを表(あらわ)します。