pinkie
The smallest finger on your hand, farthest from your thumb.
Your pinkie is your smallest finger, the one on the outside edge of your hand farthest from your thumb. It's also called your little finger, though “pinkie” is the more common name in American English.
Despite being the smallest, your pinkie does important work. Try picking up a glass of water without letting your pinkie touch it: you'll notice how much harder it becomes to grip firmly. Your pinkie helps a lot with your hand's gripping strength, working together with your ring finger to create a secure hold.
Some people can wiggle their pinkie independently, while others find it nearly impossible because of how the tendons in your hand are connected. Piano players train their pinkies to be just as strong and nimble as their other fingers, since many pieces require fast, precise pinkie work on the keys.
When two people make a promise, they sometimes hook their pinkies together in a pinkie promise or pinkie swear, a gesture that's meant to show the promise is especially serious and binding.