The difference between Appropriate and Proper

When used as adjectives, appropriate means suitable or fit, whereas proper means suited or acceptable to the purpose or circumstances.

Appropriate is also verb with the meaning: to make suitable.

Proper is also adverb with the meaning: properly.

check bellow for the other definitions of Appropriate and Proper

Appropriate as an adjective:

Suitable or fit; proper.

Examples:

"The headmaster wondered what an appropriate measure would be to make the pupil behave better."
Appropriate as an adjective:

Suitable to the social situation or to social respect or social discreetness; socially correct; socially discreet; well-mannered; proper.

Examples:

"I don't think it was appropriate for the cashier to tell me out loud in front of all those people at the check-out that my hair-piece looked like it was falling out of place."

"While it is not considered appropriate for a professor to date his student, there is no such concern once the semester has ended."
Appropriate as an adjective (obsolete):

Set apart for a particular use or person; reserved.

Appropriate as a verb (transitive, archaic):

To make suitable; to suit.

Examples:

"rfquote William Paley lang=inline=yes"
Appropriate as a verb (transitive):

To take to oneself; to claim or use, especially as by an exclusive right.

Examples:

"Let no man appropriate the use of a common benefit."
Appropriate as a verb (transitive):

To set apart for, or assign to, a particular person or use, especially in exclusion of all others; with to or for.

Examples:

"A spot of ground is appropriated for a garden."

"to appropriate money for the increase of the navy"
Appropriate as a verb (transitive, British, ecclesiastical, legal):

To annex (for example a benefice, to a spiritual corporation, as its property).

Examples:

"rfquotek Blackstone lang=en"

Proper as an adjective:

Suitable. Suited or acceptable to the purpose or circumstances; fit, suitable. Following the established standards of behavior or manners; correct or decorous.

Examples:

"the proper time to plant potatoes"

"a very proper young lady"
Proper as an adjective:

Possessed, related. Used to designate a particular person, place, or thing. Proper nouns are usually written with an initial capital letter. Pertaining exclusively to a specific thing or person; particular. In the strict sense; within the strict definition or core (of a specified place, taxonomic order, idea, etc). Belonging to oneself or itself; own. Portrayed in natural or usual coloration, as opposed to conventional tinctures. Being strictly part of some other (not necessarily explicitly mentioned, but of definitional importance) thing, and not being the thing itself. Eigen-; designating a function or value which is an eigenfunction or eigenvalue.

Examples:

"usex [[proper subset]] — [[proper ideal]]"
Proper as an adjective:

Accurate, strictly applied. Excellent, of high quality; such as the specific person or thing should ideally be. (Now often merged with later senses.) Attractive, elegant. In the very strictest sense of the word. Utter, complete.

Examples:

"Now that was a proper breakfast."

"When I realized I was wearing my shirt inside out, I felt a proper fool."

Proper as an adverb (UK, colloquial):

properly; thoroughly; completely
Proper as an adverb (nonstandard, colloquial):

properly