1. Causing or capable of causing fear; frightening: a fearful howling.
2. Experiencing fear; frightened. See synonyms at afraid.
3. Feeling or inclined to feel anxiety or apprehension; timid; nervous.
4. Indicating anxiety, fear, or terror: a fearful, nervous glance.
5. Feeling reverence, dread, or awe.
6. Extreme, as in degree or extent; dreadful: a fearful blunder; fearful poverty.

The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.