dorsal fin
noun
plural dorsal fins
: a flat thin body part that projects from the back of many fish (such as trout, barracuda, and sharks) and some marine mammals (such as dolphins)
Porpoises have a more triangular dorsal fin while a dolphin's dorsal fin is more curved.—
Naomi Corrigan and Dave Himelfield
Naomi Corrigan and Dave HimelfieldThis member of the perch family has two dorsal fins and a large mouth outfitted with sharp teeth …—Matt Markey
Matt MarkeyExamples of dorsal fin in a Sentence
Recent Examples on the Web
White sharks have a pointed dorsal fin, while basking sharks have a rounded fin.
—Rick Sobey, Hartford Courant, 22 May 2025
Related article Wild dolphins off US Southeast coast found with microplastics in their breath, study says
The Yangtze finless porpoise looks distinct, with a short snout, dark gray color and signature lack of a dorsal fin, which sets it apart from its dolphin relatives.
—Marlowe Starling, CNN Money, 14 May 2025
Both are known to swim near the ocean surface with their dorsal fin visible, but there are some key differences in appearance.
—Kathryn Varn, Axios, 11 July 2024
Additionally, basking sharks are often mistaken for great white sharks, but the latter have pointed dorsal fins, while basking sharks have rounded fins.
—Charna Flam, People.com, 28 May 2025
When mature, its dorsal fin transforms into a single spine-like illicium, which functions as a lure to attract prey.
—Scott Travers, Forbes.com, 18 May 2025
The animals have longer beaks, a more slender build and more distinctive dorsal fins than common bottlenose dolphins, according to Whale and Dolphin Conservation, a nonprofit.
—Brendan Rascius, Miami Herald, 8 May 2025
Video footage posted by the group shows one of the orcas, distinguished by its tall dorsal fin, briefly breaching the choppy surface before slipping back below the waves.
—Brendan Rascius, Miami Herald, 6 May 2025
The species is the only one in the North Pacific Ocean without a dorsal fin, and the animals can grow as large as 10 feet long and weigh 250 pounds.
—Charlotte Phillipp, People.com, 28 Feb. 2025
Examples are automatically compiled from online sources to
show current usage.
Read More
Opinions expressed in the examples do not represent those of Merriam-Webster or its editors.
Send us feedback.
Rick Sobey, Hartford Courant, 22 May 2025
Related article Wild dolphins off US Southeast coast found with microplastics in their breath, study says
The Yangtze finless porpoise looks distinct, with a short snout, dark gray color and signature lack of a dorsal fin, which sets it apart from its dolphin relatives.
—Marlowe Starling, CNN Money, 14 May 2025
Both are known to swim near the ocean surface with their dorsal fin visible, but there are some key differences in appearance.
—Kathryn Varn, Axios, 11 July 2024
Additionally, basking sharks are often mistaken for great white sharks, but the latter have pointed dorsal fins, while basking sharks have rounded fins.
—Charna Flam, People.com, 28 May 2025
When mature, its dorsal fin transforms into a single spine-like illicium, which functions as a lure to attract prey.
—Scott Travers, Forbes.com, 18 May 2025
The animals have longer beaks, a more slender build and more distinctive dorsal fins than common bottlenose dolphins, according to Whale and Dolphin Conservation, a nonprofit.
—Brendan Rascius, Miami Herald, 8 May 2025
Video footage posted by the group shows one of the orcas, distinguished by its tall dorsal fin, briefly breaching the choppy surface before slipping back below the waves.
—Brendan Rascius, Miami Herald, 6 May 2025
The species is the only one in the North Pacific Ocean without a dorsal fin, and the animals can grow as large as 10 feet long and weigh 250 pounds.
—Charlotte Phillipp, People.com, 28 Feb. 2025
Cite this Entry
“Dorsal fin.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/dorsal%20fin. Accessed 18 Jun. 2025.
Copy CitationLove words? Need even more definitions?
Merriam-Webster unabridged
Share