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.
Something, such as a railroad trestle or bridge, that extends from one point to another. The distance from the tip of the thumb to the tip of the little finger when the hand is fully extended, formerly used as a unit of measure equal to about 9 inches (23 centimeters). A period of time: a span of life. transitive verb. spanned, spanÂ·ning, spans . To extend across in space or time: a bridge that spans the gorge; a career that spanned 40 years. To encircle or cover with the hand or hands. To measure in spans. Origin of span. Middle English unit of measurement from Old English spann; see (s)pen-in Indo-European roots.