Currently, the word "pegasus" is being aliased to "pterippus", but I believe it to be unreasonable. A winged horse reminiscent of the mythical Pegasus is normally called a pegasus in fiction. Such generalization is nothing special; the same thing happened to Minotaur, Hydra, Phoenix, Cerberus and many other creatures. Even Roman authors, when describing winged horses, called them pegasi (Æthiopia produces (...) horses with wings, and armed with horns, which are called pegasi ). Oxford Dictionary permits the usage as a common noun for imaginary winged horses; maybe some others too.

On the other hand, there doesn't seem to be such a word as "pterippus". It doesn't exist in either Greek or Latin. The closest is πτερόιππος (pteroippos) but it's an adjective, which means "riding a winged horse". I strongly suspect that removing the "o" from the prefix ptero- is grammatically incorrect and "pterippus" was simply invented by a person who didn't know much about the Greek language (Rich's Pegopedia claims coinage). As far as English dictionaries go, there's dead silence.

For a time, this word was in the Wikipedia article about Pegasus, but after a discussion it was removed. Perhaps a similar discussion should take place here. I simply cannot agree with the statement that "pterippus is the true name of the species".