Im-prōp'er, a.
a. [Prefix im, not, and proper; Fr. impropre, Pr. impropri, Pg. improprio, It. improprio, impropio, Sp. impropio, Lat. improprius.]
Sense 1. Not proper; not suitable; not fitted to the circumstances, design, or end; unfit; not becoming; indecent; as, an improper medicine, regulation, &c.; improper behavior, conduct, language, words, and the like.
Sense 2. Not appropriate to individuals; general; common. [Obs.]
They are not to be adorned with any art but such improper ones as nature is said to bestow, as singing and poetry. J. Fletcher.
Sense 3. Not according to facts; inaccurate; wrong; erroneous. [Rare.]
Improper fraction (Arith.), a fraction whose denominator is less than its numerator; as, ⁴⁄₃.