fin
n. countable A2 Elementary US //ˈfɪn// UK //fˈɪn// fin
n. a thin, flat part that sticks out from the body of a fish or other water animal. It helps the animal swim, turn, and stay balanced in the water.
n. a flattened appendage or organ used by aquatic animals for locomotion, steering, and stability. Also refers to a similar fixed or movable surface on an aircraft or vehicle used for aerodynamic control.
The shark's fin appeared above the water.
Divers identified the species of the whale by the unique shape and scarring on its dorsal fin.
Engineers designed the rocket's stabilizing fins to ensure a vertical trajectory, mimicking the way a fish uses its anatomy to maintain orientation against a current.
Usage
Commonly modified by anatomical descriptors such as 'dorsal', 'pectoral', or 'caudal'.