Not proper; not suitable; not fitted to the circumstances, design, or end; unfit; not becoming; incongruous; inappropriate; indecent; as, an improper medicine; improper thought, behavior, language, dress.
- Not suited to circumstances or needs; unsuitable: improper shoes for a hike; improper medical treatment.
- Not in keeping with conventional mores; indecorous: improper behavior.
- Not consistent with established truth, fact, or rule; incorrect.
- Irregular or abnormal.