sight 
(sīt)
(sīt)n.
1.
a. The ability to see.
b. Field of vision: out of my sight.
2.
a. The act or fact of seeing: hoping for a sight of land; caught sight of a rare bird.
b. Something seen: That bird is a rare sight around here.
c. Something worth seeing; a spectacle: the sights of London.
d. Informal Something unsightly or ridiculous: looked a sight after crossing the swamp.
3. The foreseeable future; prospect: no solution in sight.
4. Mental perception or consideration: We lost sight of the purpose of our visit.
5.
a. often sights A device used to assist aim by guiding the eye, as on a firearm or surveying instrument.
b. An aim or observation taken with such a device.
v. sight·ed, sight·ing, sights
v.tr.
1. To perceive with the eyes; get sight of: sighted land after 40 days at sea.
2. To observe through a sight or an optical instrument: sight a target.
3. To adjust the sights of (a rifle, for example).
4. To take aim with (a firearm).
v.intr.
Idioms: 1. To direct one's gaze; look carefully.
2. To take aim: sighted along the barrel of the gun.
a sight Upper Southern US
A lot; much: We're a sight better off without him.
on sight
Immediately upon being seen: threatened to shoot looters on sight.
out of sight Slang
Remarkable; incredible: The graduation party was out of sight.
sight for sore eyes Informal
One whom it is a relief or joy to see.
sight unseen
Without seeing the object in question: bought the horse sight unseen.
[Middle English, from Old English sihth, gesiht, something seen; see sekw-2 in the Appendix of Indo-European roots.]