What is the meaning of Improper?

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.

Not specific or appropriate to individuals; general; common.

Of a complex random variable, correlated with its conjugate.

To appropriate; to limit.

To behave improperly

Source: wiktionary.org