earth

Concise Oxford English Dictionary © 2008 Oxford University Press:
earth/ɜːθ/

▶noun

• 1 (also Earth) the planet on which we live, the third planet of the solar system in order of distance from the sun.

• 2 the substance of the land surface; soil.

  ■ one of the four elements in ancient and medieval philosophy and in astrology.

  ■ used in names of stable, dense, non-volatile inorganic substances, e.g. fuller's earth.

  ■ literary the substance of the human body: earth to earth, ashes to ashes.

• 3 Brit. electrical connection to the ground, regarded as having zero electrical potential.

• 4 the underground lair of a badger or fox.

▶verb

• 1 Brit. connect (an electrical device) to earth.

• 2 Hunting (of a fox) run to its earth.

– phrases
bring (or come) back (down) to earth cause to return (or return) to reality.
the earth chiefly Brit. a very large amount: her hat cost the earth.
go to earth go into hiding.
on earth used for emphasis: what on earth are you doing?

– derivatives
earthward adjective & adverb,
earthwards adverb.

– origin OE eorthe, of Gmc origin.