Definitions for safety pin
Random House Webster's College Dictionary
a pin bent back on itself to form a spring, with a guard to cover the point.
Origin of safety pin:
a pin in the form of a clasp; has a guard so the point of the pin will not stick the user
Kernerman English Learner's Dictionary
safety pin(noun)ˈseɪf ti
a metal pin that has a cover for the point when it is fastened
a pin, in the form of a clasp, that has a guard to cover the sharp point; used to join two pieces of fabric etc together temporarily
the pin of a hand grenade that prevents accidental detonation
The safety pin, also known as a baby pin, is a variation of the regular pin which includes a simple spring mechanism and a clasp. The clasp serves two purposes: to form a closed loop thereby properly fastening the pin to whatever it is applied to, and to cover the end of the pin to protect the user from the sharp point. Safety pins are commonly used to fasten pieces of fabric or clothing together. They were widely used to fasten cloth diapers, as the safety clasp prevents the baby from being jabbed. Similarly, they can be used to patch torn or damaged clothing. Safety pins can also be used as an accessory or jewelry, such as earrings, chains, and wristbands. Sometimes they are used to attach an embroidered patch.