eye-shadow (n.)

c. 1200, from Old English ege (Mercian), eage (West Saxon) "eye; region around the eye; apperture, hole," from Proto-Germanic *augon (source also of Old Saxon aga, Old Frisian age, Old Norse auga, Swedish öga, Danish øie, Middle Dutch oghe, Dutch oog, Old High German ouga, German Auge, Gothic augo "eye"). Apparently the Germanic form evolved irregularly from PIE root *okw- "to see."

HAMLET: My father — methinks I see my father.

HORATIO: Where, my lord?

HAMLET: In my mind's eye, Horatio.

Until late 14c. the English plural was in -an, hence modern dialectal plural een, ene. Of potatoes from 1670s. Of peacock feathers from late 14c. As a loop used with a hook in fastening (clothes, etc.) from 1590s. The eye of a needle was in Old English. As "the center of revolution" of anything from 1760. Nautical in the wind's eye "in the direction of the wind" is from 1560s.

To see eye to eye is from Isaiah lii.8. Eye contact attested from 1953. To have (or keep) an eye on "keep under supervision" is attested from early 15c. To have eyes for "be interested in or attracted to" is from 1736; make eyes at in the romance sense is from 1837; gleam in (someone's) eye (n.) "barely formed idea" is from 1959. Eye-biter was an old name for "a sort of witch who bewitches with the eyes."

Middle English shadwe, from Old English sceadwe, sceaduwe "shade, the effect of interception of sunlight; dark image cast by someone or something when interposed between an object and a source of light," oblique cases ("to the," "from the," "of the," "in the") of sceadu (see shade (n.)). Shadow is to shade (n.) as meadow is to mead (n.2). Similar formation in Old Saxon skado, Middle Dutch schaeduwe, Dutch schaduw, Old High German scato, German schatten, Gothic skadus "shadow, shade."

From mid-13c. as "darkened area created by shadows, shade." From early 13c. in sense "anything unreal;" mid-14c. as "a ghost." Many senses are from the notion of "that which follows or attends a person." From late 14c. as "a foreshadowing, prefiguration." Meaning "imitation, copy" is from 1690s. Sense of "the faintest trace" is from 1580s; that of "a spy who follows" is from 1859. Many of the modern English senses also were in Latin umbra, Greek skia, along with that of "uninvited guest who an invited one brings with him."

As a designation of members of an opposition party chosen as counterparts of the government in power, it is recorded from 1906. Shadow of Death (c. 1200) translates Vulgate umbra mortis (Psalms xxiii.4, etc.), which translates Greek skia thanatou, itself perhaps a mistranslation of a Hebrew word for "intense darkness." In "Beowulf," Grendel is a sceadugenga, a shadow-goer, and another word for "darkness" is sceaduhelm. To be afraid of one's (own) shadow "be very timorous" is from 1580s.