An unpaired fin on the back of a fish or whale, e.g., the tall triangular fin of a shark or killer whale.
- ‘They have one caudal fin, one dorsal fin, two pelvic fins, one anal fin, and two pectoral fins.’
- ‘Thus, at this speed, the dorsal fin supplements the thrust produced by the oscillating pectoral and caudal fins.’
- ‘This is the pattern seen in the dorsal fins of fishes, in Dimetrodon and among iguanid lizards.’
- ‘They're bigger than dolphins and seals, smaller than other whales, have tall dorsal fins and are black and white.’
- ‘It has two dorsal fins and a caudal fin or tail like that of a shark.’