WordWeb Online

1. Characterized by forceful and energetic action or activity
   "a vigorous hiker"; "gave her skirt a vigorous shake"; "a vigorous campaign"; "a vigorous foreign policy"; "vigorous opposition to the war"
    
2. Strong and active physically or mentally
   "a vigorous old man who spent half of his day on horseback"

See also: energetic, ripsnorting [N. Amer], robust