imperfect

from The American Heritage® Dictionary of the English Language, 5th Edition.

• adjective Not perfect.
• adjective Grammar Of or being the tense of a verb that shows, usually in the past, an action or a condition as incomplete, continuous, or coincident with another action.
• adjective Botany Having either stamens or a pistil only. Used of a flower.
• adjective Not reproducing sexually. Used of fungi.
• adjective Law Potentially unenforceable; limited or defective.
• noun A piece of merchandise having a minor flaw that does not impair its use, usually sold at a discount.
• noun The imperfect tense.
• noun A verb in the imperfect tense.

from The Century Dictionary.

• To render imperfect.
• Not perfect; lacking completeness, correctness, or excellence; falling short of a standard or ideal; defective; incomplete: as, an imperfect copy of a book; imperfect vision.
• Characterized by or subject to defects; not completely good; frail; inadequate.
• In gram., designating incomplete or continuous action, or action or condition conceived as in process when something else takes place, as in Latin amabat, French aimait, Greek ε%27λνε, as distinguished from the simple past forms (aoristic), without further implication, amavit, aima, ε%27λνσε.
• In music. See the phrases below.
• Unjust; unfair.
• Weak, erring.
• noun In grammar, an imperfect tense; a past continuous tense.

from the GNU version of the Collaborative International Dictionary of English.

• transitive verb obsolete To make imperfect.
• noun (Gram.) The imperfect tense; or the form of a verb denoting the imperfect tense.
• adjective Not perfect; not complete in all its parts; wanting a part; deective; deficient.
• adjective Wanting in some elementary organ that is essential to successful or normal activity.
• adjective 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.
• adjective an arch of less than a semicircle; a skew arch.
• adjective (Mus.) one not ending with the tonic, but with the dominant or some other chord; one not giving complete rest; a half close.
• adjective (Mus.) chords like the third and sixth, whose ratios are less simple than those of the fifth and forth.
• adjective (Bot.) a flower wanting either stamens or pistils.
• adjective (Mus.) one a semitone less than perfect.
• adjective (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.
• adjective (Law) obligations as of charity or gratitude, which cannot be enforced by law.
• adjective (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.
• adjective (Gram.) a tense expressing past time and incomplete action.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• adjective Not perfect
• adjective botany unisexual: having either male (with stamens) or female (with pistil) flowers, but not with both.
• adjective taxonomy Known or expected to be polyphyletic, as of a form taxon.
• noun Something having a minor flaw
• noun grammar A tense of verbs used in describing a past action that is incomplete or continuous.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a tense of verbs used in describing action that is on-going
• adjective wanting in moral strength, courage, or will; having the attributes of man as opposed to e.g. divine beings
• adjective not perfect; defective or inadequate