Meaning

• A new set of hounds.

• 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.

• A series of vehicles travelling in sequence.

• A track and field discipline where runners take turns in carrying a baton from start to finish. Most common events are 4x100 meter and 4x400 meter competitions.

• An electrical actuator that allows a relatively small electrical voltage or current to control a larger voltage or current.

Meaning

• To release a new set of hounds.

• To place (people or horses) in relays, such that one can take over from another.

• To take on a new relay of horses; to change horses.

• To pass on or transfer (information).

  "Can you relay this message to John?"