Intense

Adjective

1. Of a characteristic: extreme or very high or strong in degree; severe; also, excessive, towering.
2. Of a thing: possessing some characteristic to an extreme or very high or strong degree.
3. Of feelings, thoughts, etc.: strongly focused; ardent, deep, earnest, passionate.

   "intense study"

4. Of a person: very emotional or passionate.

   "The artist was a small, intense man with piercing blue eyes."

5. Under tension; tightly drawn; strained, stressed, tense.