Headiest

adjective

1. Intoxicating or stupefying.

   "The cocktail was a heady mixture of spirits."

2. Tending to upset the mind or senses.

   "We looked out from a heady outcrop of rock."

3. Exhilarating.

   "The rock concert was a heady mixture of their greatest hits."

4. Intellectual.

   "Kierkegaard is rather heady reading for a high school student."

5. Rash or impetuous.

   "He made too heady promises, and when it came time, he was never able to fulfill them."