"extent," 1530s, "room to act," from Italian scopo "aim, purpose, object, thing aimed at, mark, target," from Latin scopus, from Greek skopos "aim, target, object of attention; watcher, one who watches" from metathesized form of PIE *spek-yo-, from root *spek- "to observe" (cognates: Sanskrit spasati "sees;" Avestan spasyeiti "spies;" Greek skopein "behold, look, consider," skeptesthai "to look at;" Latin specere "to look at;" Old High German spehhon "to spy," German spähen "to spy"). Sense of "distance the mind can reach, extent of view" first recorded c.1600.

"instrument for viewing," 1872, abstracted from telescope, microscope, etc., from Greek skopein "to look" (see scope, n.1). Earlier used as a shortening of horoscope (c.1600).