1. suitable or appropriate in the circumstances.
* "the weather was proper for the occasion"
2. (of a person, their manners, or their behavior) correct and respectable.
* "she has always been a proper lady"
3. (especially of a noun or adjective) denoting the primary, inherent, or essential qualities or characteristics of a person or thing.
* "the proper name of this city is St. Petersburg"
Etymology
late Middle English: from Old French propre, based on Latin proprius ‘one's own’, ‘peculiar’. The original sense in English was ‘belonging to one person', hence ‘exclusive’ and so ‘correct’, ‘appropriate’, and eventually ‘respectable’.