1. Showing sustained enthusiastic action with unflagging vitality
   - indefatigable, tireless, unflagging

See also: energetic

• basal vein
• basalt
• basaltic
• bascule
• base
• base hit
• base metal
• base of operations
• base on balls
• base pair
• base rate
• base runner
• base-forming
• baseball
• baseball bat
• baseball cap
• baseball card
• baseball clinic
• Averrhoa bilimbi
• Averrhoa carambola
• Averroes
• averse
• averseness
• aversion
• aversion therapy