from The American Heritage® Dictionary of the English Language, 4th Edition

  • adj. Devoid of matter; empty.
  • adj. Lacking intelligence; stupid.
  • adj. Devoid of substance or meaning; inane: a vacuous comment.
  • adj. Devoid of expression; vacant: "The narrow, swinelike eyes were open, no more vacuous in death than they had been in life” ( Nicholas Proffitt).
  • adj. Lacking serious purpose or occupation; idle. See Synonyms at empty.

from Wiktionary, Creative Commons Attribution/Share-Alike License

  • adj. Lacking meaningful content.
  • adj. Showing a lack of thought or intelligence; vacant

from the GNU version of the Collaborative International Dictionary of English

  • adj. Empty; unfilled; void; vacant.

from The Century Dictionary and Cyclopedia

  • Empty; unfilled; void; vacant.
  • Without intelligence or intelligent expression; unexpressive; showing no intelligence: as, a vacuous look.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

  • adj. devoid of intelligence
  • adj. devoid of matter
  • adj. devoid of significance or point
  • adj. void of expression


From Latin vacuus, empty; see vacuum.
(American Heritage® Dictionary of the English Language, Fourth Edition)
Latin vacuus ("empty, vacant") (Wiktionary)



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  • One knows one's madnesses, by and large. By and large the knowledge is vacuous. The notion of naming the beast to conquer it is the idiot optimism of psychotherapy. From "The Last Werewolf" by Glen Duncan.

    March 3, 2012

  • I don't think I would describe a house as "vacuous" -- a face, an expression, a mind, yes, but not a house. For a house I would use the word "vacant". In fact, checking the Oxford American Dictionary, I see that, under "vacuous", the meaning "empty" is marked as "archaic".

    October 31, 2010

  • Empty: The house was vacuous after the family left. (newbury house dic)

    October 30, 2010

  • This word *perfectly* describes the face of one of my students. Some days I want to walk over and check his pulse.

    September 21, 2007