Switchblade (noun)

1. A type of knife with a folding blade that can be opened by pressing a button or lever.
2. A switchblade knife.

Origin:

Originated from 1940s; a blend of switch and blade.

Examples:

1. The young man carried a switchblade for protection.
2. The switchblade was banned in many countries due to its association with violent crime.
3. The salesman demonstrated the quick deployment of the switchblade.
4. The switchblade was used to cut through the thick rope.
5. The switchblade was hidden in the back pocket of the man's jeans.