span [OE] Span as a measure of distance was originally a ‘distance between the tips of the thumb and little finger’. Of Germanic origin, it was rare in Old English but was reinforced from c.1300 by Old French version espan. The meaning ‘a short space of time’ (mortal span) dates from the late 16th century. The word was applied to the ‘arch of a bridge’ from the early 17th century.