Noun

1. The act of passing something along from one person or group to another
2. A crew of workers who relieve another crew
3. A fresh team to relieve weary draft animals
4. A race between teams; each member runs or swims part of the distance
5. Electrical device such that current flowing through it in one circuit can switch on and off a current in a second circuit

Verb

1. Pass along
2. Control or operate by relay