Balk (verb)

1. To stop abruptly, often in a stubborn or obstinate way.
2. To refuse to do something, often in a sudden or unexpected way.
3. To hesitate or falter in a sports context, such as in baseball when a pitcher commits a balk.

Origin:

From middle english "balken" meaning to stop suddenly, from old norse "balkr" meaning beam, from proto-germanic "balkaz" meaning beam.

Examples:

1. He balked at the idea of going on vacation.
2. She balked when she saw the long line at the store.
3. The horse balked at the jump and refused to go over it.
4. The pitcher was called for a balk after he hesitated on the mound.
5. The team was ready to sign the contract, but the player balked at the last minute.