stubborn; dogged; persistent; tenacious
tough; sturdy; hardy; strong
頑強な抵抗を続けて敵を退けた。
They repelled the enemy by offering tenacious resistance.
彼は頑強な体力の持ち主だ。
He possesses remarkable physical toughness.
頑強に主張を曲げない姿勢が評価された。
His tenacious refusal to bend was appreciated.