Definition of middle earth in US English:

middle earth

noun

  • The world, the earth, regarded as a middle region between heaven and hell, or as occupying the centre of the universe. Sometimes also: the inhabitants or things of the world, especially as opposed to those of heaven; worldly things as opposed to divine or spiritual things. In later use chiefly archaic or literary.

Origin

Middle English; earliest use found in Layamon (fl. 1250), poet. From middle + earth.

Pronunciation

middle earth

/ˌmɪd(ə)l ˈəːθ/