a flattened appendage on various parts of the body of many aquatic vertebrates, including fish and cetaceans, and used for propulsion, steering, and balance in the water, a projecting vertical surface on an aircraft, contributing to directional control

split fins, dorsal fin, tail fin

Formal and Informal Expressions of fins

In different contexts, you can replace 'fins' with suitable alternatives. In a more formal setting, 'appendage' is apt. In informal speech or writing, 'flippers' is a commonplace synonym.

fins: Explore its Definition & Usage

fins Definition

1a flattened appendage on various parts of the body of many aquatic vertebrates, including fish and cetaceans, and used for propulsion, steering, and balance in the water
2a projecting vertical surface on an aircraft, contributing to directional control

Using fins: Examples

Take a moment to familiarize yourself with how "fins" can be used in various situations through the following examples!

Example
The shark's dorsal fin was visible above the water.
Example
The airplane's tail fin helps it stay on course.
Example
The scuba diver wore fins on his feet to swim faster.

fins Synonyms and Antonyms

Synonyms for fins

flippers
paddles
rudders

Phrases with fins

split fins
a type of diving fin that is designed to reduce drag and increase efficiency
Example
Split fins are popular among scuba divers because they require less effort to move through the water.
dorsal fin
the fin on the back of a fish or cetacean
Example
The dorsal fin of the killer whale can be up to six feet tall.
tail fin
the fin at the rear of an aircraft or boat, used for stabilization and steering
Example
The tail fin of the airplane was painted with the company logo.

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Summary: fins in Brief

The term 'fins' [fɪnz] refers to flattened appendages found on aquatic vertebrates such as fish and cetaceans, as well as on aircraft. Fins are used for propulsion, steering, and balance in the water, and contribute to directional control in aircraft. Examples include the dorsal fin on a shark and the tail fin on an airplane.