Improper and Invalid

Improper adjective - Not appropriate for a particular occasion or situation.

Invalid and improper are semantically related In some cases you can use "Invalid" instead an adjective "Improper".

Nearby Word: improperly

Invalid adjective - Chronically or repeatedly suffering from poor health.

Improper and invalid are semantically related in illegitimate topic. Sometimes you can use "Improper" instead an adjective "Invalid".

Nearby Words: invalidate, invalidated, invalidity, invalided, invalidation