stren·u·ous 
(strĕny-əs)
(strĕny-əs)adj.
1. Requiring great effort, energy, or exertion: a strenuous task.
2. Vigorously active; energetic or zealous: strenuous efforts.
[From Latin strēnuus.]
strenu·ous·ly adv.
strenu·ous·ness n.
- front-end load
- front-end loader
- frontenis
- frontes
- frontier
- frontiersman
- frontierswoman
- frontispiece
- frontlet
- frontline
- frontlist
- front-load
- frontman
- front matter
- front money
- front nine
- front office
- frontogenesis
- frontolysis
- fronton
- frontotemporal
- frontotemporal dementia
- front-page
- Front Range
- front room