1Superior, first-class, excellent; of high quality or grade.
これは上等なワインだから大切に保管しよう。
This is a fine wine, so let's store it carefully.
上等な布地を使ったスーツは着心地が違う。
A suit made from top-quality fabric feels different to wear.
彼の仕事ぶりは上等だと評価された。
His work was rated as excellent.
2An interjection meaning 'that's fine!' or 'bring it on!'; a blunt, casual response used to accept a challenge or show defiance.
『手伝ってくれないの？』『上等だ、一人でやってやる』
"You won't help me?" "Fine, I'll do it myself!"
そんなことを言うなら、やってみろ、上等だ。
If you're going to say that, then go ahead and try it — bring it on.