exasecond

/IH0 G Z AA1 S AH0 K AA1 N D/
noun
  1. 1

    (metrology) An SI unit of time equal to 10¹⁸ seconds. Symbol: Es. (= 31 709 800 000 years, which is more time than has elapsed in the Universe, that is, since the Big Bang [about 13 800 000 000 years].)