One woman who was not married to a President but who is still considered an official First Lady: Harriet Lane, niece of bachelor James Buchanan. The other non-spousal relatives who served as White House hostesses are not recognized by the First Ladies' Library.
Any distance between two things is called a span. These end points can be physical, like the span of a rope between two trees, or they can be more abstract, such as the span of time between five and six o'clock. Span comes from the Old English spann, the width of the stretched-out hand, measured from thumb to little finger.
Freebase(0.00 / 0 votes)Rate this definition: Span of control. Span of control is the term now used more commonly in business management, particularly human resource management. Span of control refers to the number of subordinates a supervisor has. In the hierarchical business organization of some time in the past it was not uncommon to see average spans of 1 to 4 or even less.