'Improper diphthong' definitions:

Definition of 'Improper diphthong'

From: GCIDE
  • Improper \Im*prop"er\, a. [F. impropre, L. improprius; pref. im- not + proprius proper. See Proper.]
  • 1. Not proper; not suitable; not fitted to the circumstances, design, or end; unfit; not becoming; incongruous; inappropriate; indecent; as, an improper medicine; improper thought, behavior, language, dress. [1913 Webster]
  • Follow'd his enemy king, and did him service, Improper for a slave. --Shak. [1913 Webster]
  • And to their proper operation still, Ascribe all Good; to their improper, Ill. --Pope. [1913 Webster]
  • 2. Not peculiar or appropriate to individuals; general; common. [Obs.] [1913 Webster]
  • Not to be adorned with any art but such improper ones as nature is said to bestow, as singing and poetry. --J. Fletcher. [1913 Webster]
  • 3. Not according to facts; inaccurate; erroneous. [1913 Webster]
  • Improper diphthong. See under Diphthong.
  • Improper feud, an original feud, not earned by military service. --Mozley & W.
  • Improper fraction. See under Fraction. [1913 Webster]

Definition of 'improper diphthong'

From: GCIDE
  • Diphthong \Diph"thong\ (?; 115, 277), n. [L. diphthongus, Gr. ?; di- = di`s- twice + ? voice, sound, fr. ? to utter a sound: cf. F. diphthongue.] (Ortho["e]py) (a) A coalition or union of two vowel sounds pronounced in one syllable; as, ou in out, oi in noise; -- called a proper diphthong. (b) 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. [1913 Webster]