startle

American Heritage® Dictionary of the English Language, Fourth Edition

1. v. To cause to make a quick involuntary movement or start.
2. v. To alarm, frighten, or surprise suddenly. See Synonyms at frighten.
3. v. To become alarmed, frightened, or surprised.
4. n. A sudden mild shock; a start.

Century Dictionary and Cyclopedia

1. To start; manifest fear, alarm, surprise, pain, or similar emotion by a sudden involuntary start.
2. To wince; shrink.
3. To move suddenly, as if surprised or frightened.
4. To take to flight, as in panic; stampede, as cattle.
5. To take departure; depart; set out.
6. To cause to start; excite by sudden surprise, alarm, apprehension, or other emotion; scare; shock.
7. To rouse suddenly; cause to start, as from a place of concealment or from a state of repose or security.
8. n. A sudden movement or shock caused by surprise, alarm, or apprehension of danger; a start.

Wiktionary

1. n. A sudden motion or shock caused by an unexpected alarm, surprise, or apprehension of danger.
2. v. To move suddenly, or be excited, on feeling alarm; to start.
3. v. To excite by sudden alarm, surprise, or apprehension; to frighten suddenly and not seriously; to alarm; to surprise.
4. v. To deter; to cause to deviate.

GNU Webster's 1913

1. v. To move suddenly, or be excited, on feeling alarm; to start.
2. v. To excite by sudden alarm, surprise, or apprehension; to frighten suddenly and not seriously; to alarm; to surprise.
3. v. To deter; to cause to deviate.
4. n. A sudden motion or shock caused by an unexpected alarm, surprise, or apprehension of danger.

WordNet 3.0

1. v. to stimulate to action
2. v. move or jump suddenly, as if in surprise or alarm
3. n. a sudden involuntary movement