- 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.
- Not to be adorned with any art but such improper ones as nature is said to bestow, as singing and poetry.
- French: impropre, inconvenant, grossier
- German: unhöflich
- Portuguese: impróprio, indecente, indecoroso
- Russian: непристо́йный
improper (impropers, present participle impropering; past and past participle impropered)
- (obsolete, transitive) To appropriate; to limit.
- He would in like manner improper and inclose the sunbeams to comfort the rich and not the poor.
- (obsolete) To behave improperly