One who snitches or informs on someone to a person of higher authority. Originally street slang for someone who informs to the police, it refers to the old price of using a public payphone (10 cents). Primarily heard in US, South Africa. I bet Timmy's the dime-dropper—he's such a teacher's pet, always ready to tattle on any of the other students he thinks are misbehaving. He knew he was facing 10 years in prison, so he agreed to be a dime-dropper for the police in exchange for a lighter sentence.

slang Someone who frequently or habitually uses or abuses drugs prepared as pills or capsules. She started getting hooked on the pain pills her doctor prescribed, and before long she had become a full-blown pill dropper. I knew a couple of pill droppers in college who were always doing speed or ecstasy.