What does "imperfect" mean?

Additional senses

1. 2.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.
2. 3.The imperfect tense; or the form of a verb denoting the imperfect tense.
3. 4.To make imperfect. [Obs.]