vigorous

 
Pronunciation: /ˈvɪg(ə)rəs/

adjective

  • strong, healthy, and full of energy: a tall, vigorous, and muscular man
  • characterized by or involving physical strength, effort, or energy: vigorous aerobic exercise
  • (of language) forceful: a vigorous denial

Derivatives

vigorousness

noun

Origin:

Middle English: via Old French from medieval Latin vigorosus, from Latin vigor (see vigour)

Spelling rule

If a word ends in -our (in this case vigour), change -our to -or before adding -ous and some other endings: vigorous.