Merriam-Webster Collegiate Dictionary - mister

 I. noun  Etymology: alteration of 1master  Date: 1551  1. capitalized Mr. — used sometimes in writing instead of Mr.  2. sir — used without a name as a generalized term of direct address of a man who is a stranger hey, ~, do you want to buy a paper  3. a man not entitled to a title of rank or an honorific or professional title though he was only a ~, he was a greater scholar in his field than any PhD  4. husband  II. noun  Etymology: 2mist + 2-er  Date: 1973 a device for spraying a mist