from The American Heritage® Dictionary of the English Language, 5th Edition.

  • noun A complex speech sound or glide that begins with one vowel and gradually changes to another vowel within the same syllable, as (oi) in boil or (ī) in fine.

from The Century Dictionary.

  • noun A coalition or union of two vowels pronounced in one syllable.
  • To sound as a diphthong; diphthongize.

from the GNU version of the Collaborative International Dictionary of English.

  • transitive verb rare To form or pronounce as a diphthong; diphthongize.
  • noun A coalition or union of two vowel sounds pronounced in one syllable; as, ou in out, oi in noise; -- called a proper diphthong.
  • noun A vowel digraph; a union of two vowels in the same syllable, only one of them being sounded; as, ai in rain, eo in people; -- called an improper diphthong.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

  • noun phonetics A complex vowel sound that begins with the sound of one vowel and ends with the sound of another vowel, in the same syllable.
  • noun rare A vowel digraph or ligature.

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

  • noun a vowel sound that starts near the articulatory position for one vowel and moves toward the position for another


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

[Middle English diptonge, from Old French diptongue, from Late Latin diphthongus, from Greek diphthongos : di-, two; see di– + phthongos, sound.]

from Wiktionary, Creative Commons Attribution/Share-Alike License

French diphtongue, from Ancient Greek δίφθογγος (diphthongos, "two sounds"), from δίς (dis, "twice") + φθόγγος (phthongos, "sound").


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  • I keep wanting to pronounce this "dip thong", which is rather funny really.

    December 2, 2007

  • This is a condition best treated by an opthalmologist.

    December 2, 2007

  • Ahhhhhhhhhh.. I see it now!

    December 2, 2007

  • Or an ophthalmologist. ;-)

    December 3, 2007

  • in an amp(h)itheatre!

    December 3, 2007

  • Or diphtheria...

    December 4, 2007

  • ... phthisis ... treatable with a phthalein

    June 20, 2008

  • Thanks for the new fodder for this list, jmp.

    June 20, 2008

  • Dip your thong in water and you will have a wet article of undergear.

    August 9, 2008