dorsal fin

American  

noun

1. the fin or finlike integumentary expansion generally developed on the back of aquatic vertebrates.

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dorsal fin British  

noun

1. any unpaired median fin on the backs of fishes and some other aquatic vertebrates: maintains balance during locomotion

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Etymology

Origin of dorsal fin

First recorded in 1760–70

Example Sentences

"One of the sightings reported a group of single male outer coast orcas slapping each other with their dorsal fins and charging at inner coast females."

From Science Daily

They crawled around blowholes and dorsal fins, and soon each human was sitting on the back of their very own whale.

From Literature

Each encounter was carefully recorded, and the individual orcas were identified by markings on their dorsal fins.

From Science Daily

"A dorsal fin slowly broke the surface revealing that familiar profile that looked like a shark," he said.

From BBC

Winter had put a life vest on the dog resembling a shark, with a dorsal fin protruding from its back.

From Los Angeles Times