1the full extent of something from end to end; the amount of space that something covers:a warehouse with a clear span of 28 feet the wingspan of an aircraft or a bird: the gannets had black-tipped wings with a six-foot span an arch or part of a bridge between piers or supports: a major setback was the collapse of one span of a flyover an eight-span bridge (also handspan) the maximum distance between the tips of the thumb and little finger, taken as the basis of a measurement equal to 9 inches.
2the length of time for which something lasts:a short concentration span archaic a short distance or time. 1 [with object] (of a bridge, arch, etc.) extend from side to side of:the stream was spanned by a narrow bridge cover or enclose with the length of one’s hand:her waist was slender enough for him to span with his hands
2extend across (a period of time or a range of subjects):their interests span almost all the conventional disciplines