Definition of well-rested in US English:

well-rested

adjective

  • Having had plenty of rest; very refreshed.

Origin

Early 16th century; earliest use found in 2nd Baron Berners (c1467–1533), soldier, diplomat, and translator. From well + rested.

Pronunciation

well-rested

/ˌwɛlˈrɛstɪd/