Meaning of eyeopener

eye•o•pen•er

Pronunciation: (ī'ō"pu-nur), [key]
— n.
  1. an experience or disclosure that gives one a sudden realization or understanding: Her disclosures about her childhood were a real eyeopener.
  2. a drink of liquor taken early in the day and intended to wake a person up fully.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.