1. A small marine organism with a shell that clings to rocks and ships.
2. A clinging or dependent person or thing
3. A large zit or scab
4. An exclimation used by Sponge Bob Square Pants meaning "shit" or "fuck"
1. Based on the number of barnacles stuck to this sunken ship, I deduce that it must have been here for a while.
2. God, I hate Henry! The little barnacle won't leave me alone!
3. Did you see the barnacle on Lisa's face?! It was huge!
4. Patrick: "I'm not actually gay, Sponge Bob."
Sponge Bob: "Oh barnacles!!"