Im·per·fect a.
  1. Not perfect; not complete in all its parts; wanting a part; deective; deficient.
     Something he left imperfect in the state.   --Shak.
     Why, then, your other senses grow imperfect.   --Shak.
  2. Wanting in some elementary organ that is essential to successful or normal activity.
     He . . . stammered like a child, or an amazed, imperfect person.   --Jer. Taylor.
  3. Not fulfilling its design; not realizing an ideal; not conformed to a standard or rule; not satisfying the taste or conscience; esthetically or morally defective.
  Nothing imperfect or deficient left
  Of all that he created.   --Milton.
  Then say not man's imperfect, Heaven in fault;
  Say rather, man's as perfect as he ought.   --Pope.
  Imperfect arch, an arch of less than a semicircle; a skew arch.
  Imperfect cadence Mus., one not ending with the tonic, but with the dominant or some other chord; one not giving complete rest; a half close.
  Imperfect consonances Mus., chords like the third and sixth, whose ratios are less simple than those of the fifth and forth.
  Imperfect flower Bot., a flower wanting either stamens or pistils. --Gray.
  Imperfect interval Mus., one a semitone less than perfect; as, an imperfect fifth.
  Imperfect number Math., a number either greater or less than the sum of its several divisors; in the former case, it is called also a defective number; in the latter, an abundant number.
  Imperfect obligations Law, obligations as of charity or gratitude, which cannot be enforced by law.
  Imperfect power Math., a number which can not be produced by taking any whole number or vulgar fraction, as a factor, the number of times indicated by the power; thus, 9 is a perfect square, but an imperfect cube.
  Imperfect tense Gram., a tense expressing past time and incomplete action.
  imperfect tense
       n : a tense of verbs used in describing action that is on-going
           [syn: progressive, progressive tense, imperfect, continuous
           tense]