'Improper fraction' definitions:

Definition of 'improper fraction'

noun

A fraction whose numerator is larger than the denominator

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]