noun

• (hunting, rare) A new set of hounds.
• (now chiefly historical) A new set of horses kept along a specific route so that they can replace animals that are tired.
• (by extension) A new set of anything.
  "There is a snaky gleam in her hard grey eye, as of anticipated rounds of buttered toast, relays of hot chops, worryings and quellings of young children, sharp snappings at poor Berry, and all the other delights of her Ogress's castle."
• (sports) A competition between teams where members of a team take turns completing parts of a course or performing a certain action.

verb

• (transitive) To pass on or transfer (information).
  "The CCTV cameras relay what's going on to the headquarters."
• (obsolete, intransitive, hunting) To release a new set of hounds.
• (transitive, now rare) To place (people or horses) in relays, such that one can take over from another.
• (intransitive, now rare) To take on a new relay of horses; to change horses.