greyhound (n.) Look up greyhound at Dictionary.com
Old English grighund, from grig- "bitch" + hund "dog" (see hound (n.)). The name usually is said to have nothing to do with color, and most are not gray. The Old Norse form of the word is preserved in Hjalti's couplet that almost sparked war between pagans and Christians in early Iceland:
Vilkat goð geyja
grey þykkjumk Freyja


I will not blaspheme the gods,
but I think Freyja is a bitch