vig·or 
(vĭgər)
(vĭgər)n.
1. Physical or mental strength, energy, or force: Our vigor was depleted by the hot weather.
2. The capacity for natural growth and survival, as of plants or animals.
3. Strong feeling; enthusiasm or intensity: argued his point with great vigor.
[Middle English, from Old French, from Latin, from vigēre, to be lively; see weg- in the Appendix of Indo-European roots.]
Synonyms: vigor, dash1, punch2, verve, vim, vitality
These nouns denote a quality of spirited force or energy: intellectual vigor; played the piano with dash; an editorial with real punch; painted with verve; arguing with his usual vim; a decreased mental vitality.
These nouns denote a quality of spirited force or energy: intellectual vigor; played the piano with dash; an editorial with real punch; painted with verve; arguing with his usual vim; a decreased mental vitality.