Unicorned

To the second series belong the unicorned and bicorned species of Asia.

Source: wiktionary

Doctor Shepard related in his book that unicorned sheep exist in Nepal and on occasion are even sent to Europe.

Source: wiktionary

Here may be the explanation of the one-horned cows and bulls that Aelian says were to be found in Ethiopia and of the unicorned cattle reported by Pliny as living in the land of the Moors.

Source: wiktionary

Clearly a unicorned animal could be produced by bending an animal's horns inwards as they grew and twisting them together, or, presumably, by removing one horn and manipulating the other.

Source: wiktionary