extraterrestrial /(ĕks`trȧ*tĕr`rĕs"trĭ*al)/

ex·tra·ter·res·tri·al

extraterrestrial

adj.
  1. originating or located or occurring outside Earth or its atmosphere; as, there is no clear evidence for extraterrestrial life.

extraterrestrial

n.
  1. a hypothetical form of life existing outside the Earth or its atmosphere, especially intelligent life on other planets or in other solar systems; as, what would you say to an extraterrestrial?.