Proper

From Anglo-Norman proper, propre, Old French propre (French: propre), and their source, Latin proprius.

Full definition of proper

Suited or acceptable to the purpose or circumstances; fit, suitable. from 13th c.
the proper time to plant potatoes

Alexander Pope (1688-1744)The proper study of mankind is man.
2014-06-14, It's a gas, One of the hidden glories of Victorian engineering is proper drains. Isolating a cityâ€™s effluent and shipping it away in underground sewers has probably saved more lives than any medical procedure except vaccination.

Following the established standards of behavior or manners; correct or decorous. from 18th c.
a very proper young lady

1910, Emerson Hough, The Purchase Price Chapter 1, This new-comer was a man who in any company would have seemed striking....Indeed, all his features were in large mold, like the man himself, as though he had come from a day when skin garments made the proper garb of men.

(grammar) Used to designate a particular person, place, or thing. Proper words are usually written with an initial capital letter. from 14th c.
Pertaining exclusively to a specific thing or person; particular. from 14th c.

1621, Robert Burton, The Anatomy of Melancholy, II.1.3:They have a proper saint almost for every peculiar infirmity: for poison, gouts, agues ...
Samuel Taylor Coleridge (1772-1834)those high and peculiar attributes ... which constitute our proper humanity

William Shakespeare (1564-1616)my proper son
John Dryden (1631-1700)Now learn the difference, at your proper cost,
Betwixt true valour and an empty boast.
1621, Robert Burton, The Anatomy of Melancholy, II.4.1.ii:every country, and more than that, every private place, hath his proper remedies growing in it, particular almost to the domineering and most frequent maladies of it.
1946, Bertrand Russell, A History of Western Philosophy, I.20:Each animal has its proper pleasure, and the proper pleasure of man is connected with reason.

(heraldry) Portrayed in natural or usual coloration, as opposed to conventional tinctures. from 16th c.
(mathematics, physics) Eigen-; designating a function or value which is an eigenfunction or eigenvalue. from 20th c.
Accurate, strictly applied.

Excellent, of high quality; such as the specific person or thing should ideally be. (Now often merged with later senses.) from 14th c.
Now that was a proper breakfast.
(now regional) Attractive, elegant. from 14th c.

1526, William Tyndale, trans. Bible, Acts VII:The same tyme was Moses borne, and was a propper childe in the sight of God, which was norisshed up in his fathers housse thre monethes.

In the very strictest sense of the word (now often as postmodifier). from 14th c.

Joyce Ulysses, Episode 16:Though unusual in the Dublin area he knew that it was not by any means unknown for desperadoes who had next to nothing to live on to be abroad waylaying and generally terrorising peaceable pedestrians by placing a pistol at their head in some secluded spot outside the city proper ....

(now colloquial) Utter, complete. from 15th c.
When I realized I was wearing my shirt inside out, I felt a proper fool.

1964, Saint Andrew Society (Glasgow, Scotland), The Scots magazine: Volume 82Don't you think you must have looked proper daft?

2012, Soufside, Hello (song)When I meet a bad chick, know I gotta tell her hellotalk real proper, but she straight up out the ghetto