Definitions for earplugˈɪərˌplʌg
Random House Webster's College Dictionary
a plug of soft, pliable material inserted into the opening of the outer ear, esp. to keep out water or noise.
Origin of earplug:
A piece of protective clothing that is meant to be inserted in the ear canal to protect the wearer's hearing from loud noises or the intrusion of water
To fit with earplugs.