Is there a spelled-out version of...

Mrs. is an abbreviation for mistress. In early England, missis and missus were used in place of the more formal mistress. By the 17th century, they had been replaced by Mrs., at least in written form. In time, Mrs. alone was deemed rather disrespectful and was used only when attached to a name. If you wish to write the abbreviation as it is said, missus would be correct. As in the past, however, it has a rather disrespectful connotation when used alone.