It means very fast raptor. It means he grabs very fast with his claws. It is the name of a genus of birds of the Apodidae family. They are known as large swifts, royal swifts or equatorial swifts.
Tachymarptis : Genus of birds apodiformes of the family of apodiddes; they are large swifts, with wide wings, large heads and forked tails.