Stimulant (noun)

1. A substance that temporarily quickens some vital process, such as respiration or the heart rate, or produces a feeling of euphoria.
2. Something that incites or rouses to action.

Origin:

Late 18th century: from latin stimulant- "stirring up", from the verb stimulare.

Examples:

1. Caffeine is a stimulant found in coffee and tea.
2. Some athletes use stimulants to enhance their performance.
3. He was taking a stimulant to stay awake.
4. The economy needs a stimulant to revive it.
5. The new law is meant to be a stimulant for the economy.