Black's Law Dictionary (2nd edition)dictionaries

Mark

1. A character, usually in the form of a cross, made as a substitute for his signature by a person who cannot write, in executing a conveyance or other legal docu-ment. It is commonly made as follows: A third person writes the name of the marksman, leaving a blank space between the Christian name and surname; in this space the latter traces the mark, or crossed lines, and above the mark is written “his,” (or “her,”) and below it, “mark.”

Source: Black’s Law Dictionary 2nd Ed (1910)