Fetching details from the dictionary...

burly; strong; sturdy
indomitable; indefatigable; strong-willed; resolute; bold
robust (vitality, appetite, economic growth, etc.); strong
逞しく成長した息子を見て喜んだ。
I was happy to see my son grow up strong.
逞しい精神力で困難を乗り越えた。
I overcame difficulties with strong willpower.
逞しい体つきの男が倉庫で重い荷物を運んでいた。
A muscular man was carrying heavy cargo in the warehouse.