stimulant
noun /ˈstɪmjələnt/
  /ˈstɪmjələnt/
 (formal)- a drug or substance that makes you feel more active and gives you more energy- Coffee and tea are mild stimulants.
 
- stimulant (to something) an event or activity that encourages more activity
Word Originearly 18th cent.: from Latin stimulant- ‘urging, goading’, from the verb stimulare.