"Verily, truth is sight. Therefore if two people should come disputing, saying, 'I have seen,' 'I have heard,' we should trust the one who says 'I have seen.' " [Brhadaranyaka Upanishad 5.14.4]Sight for sore eyes "welcome visitor" is attested from 1738; sight unseen "without previous inspection" is from 1892. Sight gag first attested 1957.
The ability to see.
Field of vision.