Rigorous means harsh, precise, severe, or strict. (see also Rigid vs Rigorous vs Strict vs Stringent )
- The selection process is based on rigorous tests of competence and experience.
- Taxis must conform to the rigorous standards laid down by the police.
- He is rigorous in his control of expenditure.
Vigorous means energetic, robust, or strong. (see also Vigorish vs Vigorous )
- Take vigorous exercise for several hours a week.
- This plant is a vigorous grower.
- African dance is vigorous, but full of subtlety.