fin

/fɪn/
verb
  1. To swim by moving fins, or to move through water like a fish.
    • We finned our way to the surface after exploring the underwater cave.
    • The fish finned against the current to reach its spawning ground.
    • The scuba diver finned slowly through the coral reef.
noun
  1. A thin, flat part on the body of a fish, dolphin, or other aquatic animal, used for swimming and steering.
    • The dolphin used its tail fin to propel itself out of the water.
    • The goldfish fluttered its fins gracefully as it circled the bowl.
    • The shark's dorsal fin cut through the water as it swam near the boat.
  2. A flat, usually vertical part attached to a vehicle or device for stability or control, such as on an airplane, car, or rocket.
    • The old car had large fins on the back, which were popular in the 1950s.
    • The rocket's fins guided it through the atmosphere.
    • The airplane's tail fin helps keep it stable during flight.
  3. A five-dollar bill (slang).
    • She found a fin on the sidewalk and picked it up.
    • I only had a fin in my pocket, so I couldn't buy the book.
    • He handed me a fin to pay for the coffee.
Synonyms
What does "fin" mean? | whatsthatwordmean | whatsthatwordmean