Definition of middle earth in English:

middle earth

Pronunciation /ˌmɪd(ə)l ˈəːθ/

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. Compare "middenerd", "middle-erd", mid-earth .

Origin

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