As a noun improver
is something that, or someone who, improves.
As an adjective improper is
unsuitable to needs or circumstances; inappropriate; inapt.
As a verb improper is
(obsolete|transitive) to appropriate; to limit.
Other Comparisons: What's the difference?
Something that, or someone who, improves
A substance added to cause improvement (especially to a foodstuff)
* impropre (obsolete)
unsuitable to needs or circumstances; inappropriate; inapt
Not in keeping with conventional mores or good manners; indecent or immodest
Not according to facts; inaccurate or erroneous
Not consistent with established facts; incorrect
Not properly named; See, for example, improper fraction
(obsolete) Not specific or appropriate to individuals; general; common.
* J. Fletcher
- Not to be adorned with any art but such improper ones as nature is said to bestow, as singing and poetry.
* improper divisor
* improper face
* improper fit
* improper fraction
* improper integral
* improper motion
* improper node
* improper orthogonal transformation
* improper rotation
* improper use
* improper workmanship
(obsolete) To appropriate; to limit.
(obsolete) To behave improperly
- He would in like manner improper and inclose the sunbeams to comfort the rich and not the poor.