[n. ree-ley; v. ree-ley, ri-ley] 
noun, verb, -layed, -lay⋅ing.| 1. | a series of persons relieving one another or taking turns; shift. |
| 2. | a fresh set of dogs or horses posted in readiness for use in a hunt, on a journey, etc. |
| 3. | Sports.
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| 4. | Machinery. an automatic control device in which the settings of valves, switches, etc., are regulated by a powered element, as a motor, solenoid, or pneumatic mechanism actuated by a smaller, sensitive element. |
| 5. | Electricity. a device, usually consisting of an electromagnet and an armature, by which a change of current or voltage in one circuit is used to make or break a connection in another circuit or to affect the operation of other devices in the same or another circuit. |
| 6. | (initial capital letter ) U.S. Aerospace. one of an early series of experimental low-altitude, active communications satellites. |
| 7. | to carry forward by or as if by relays: to relay a message. |
| 8. | to provide with or replace by fresh relays. |
| 9. | Electricity. to retransmit (a signal, message, etc.) by or as if by means of a telegraphic relay. |
| 10. | Electricity. to retransmit a signal or message electronically. |
| relay (rē'lā) Pronunciation Key
An electrical switch that is operated by an electromagnet, such as a solenoid. When a small current passes through the electromagnet's coiled wire, it produces a magnetic field that attracts a movable iron bar, causing it to pivot and open or close the switch. |