- (nonstandard) superlative form of : most proper.
1749, Henry Fielding, The History of Tom Jones, a Foundling, London: A[ndrew] Millar, OCLC 928184292:
- “Very probably,” answered Partridge; “but if the top of the hill be properest to produce melancholy thoughts, I suppose the bottom is the likeliest to produce merry ones, and these I take to be much the better of the two. […]
1814 July, [Jane Austen], chapter VIII, in Mansfield Park, volume I, London: T[homas] Egerton, OCLC 39810224, page 156:
- […] Mr. Rushworth discovered that the properest thing to be done, was for him to walk down to the Parsonage directly, and call on Mr. Crawford, and inquire whether Wednesday would suit him or not.