span (v.)youdaoicibaDictYouDict
Old English spannan "to join, link, clasp, fasten, bind, connect; stretch, span," from Proto-Germanic *spannan (cognates: Old Norse spenna, Old Frisian spanna, Middle Dutch spannen, Dutch spannan "stretch, bend, hoist, hitch," Old High German spannan, German spannen "to join, fasten, extend, connect"), from PIE root *(s)pen- "to draw, stretch, spin" (cognates: Latin pendere "to hang, to cause to hang," pondus "weight" (perhaps the notion is the weight of a thing measured by how much it stretches a cord), pensare "to weigh, consider;" Greek ponos "toil," ponein "to toil;" Lithuanian spendziu "lay a snare;" Old Church Slavonic peti "stretch, strain," pato "fetter," pina "I span;" Old English spinnan "to spin;" for other cognates, see spin (v.)).

The meaning "to encircle with the hand(s)" is from 1781; in the sense of "to form an arch over (something)" it is first recorded 1630s. Related: Spanned; spanning.