/gray"hownd'/ , n.
1. one of a breed of tall, slender, short-haired dogs, noted for its keen sight and swiftness.
2. a swift ship, esp. a fast ocean liner.
Also, grayhound .
[ bef. 1000; ME greihund, grehund, grihund, OE grighund greyhundr; cf. ON grey bitch; see HOUND 1 ]