strenuous

adjective
1
needing great effort and energy
طاقت‌فرسا, سخت, پرزحمت, دشوار
synonym arduous
2
determined and showing great energy
پرتلاش, سخت‌کوش, خستگی‌ناپذیر, نستوه
The ship went down although strenuous efforts were made to save it.
The plan has met with strenuous opposition.