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.
1 the interval, space, or distance between two points, such as the ends of a bridge or arch. 2 the complete duration or extent. the span of his life. 3 (Psychol) the amount of material that can be processed in a single mental act. apprehension span, span of attention. 4 short for â wingspan.