Noun

1. A device to assist in motion as a cane, especially one that provides support under the arm to reduce weight on a leg.

   He walked on crutches for a month until the cast was removed from his leg.

2. Something that supports, often used negatively to indicate that it is not needed and causes an unhealthful dependency; a prop

   Alcohol became a crutch to help him through the long nights; eventually it killed him.