1946 as an extreme snow condition on the U.S. prairie, from white as a verb + out (adv.). From 1977 as a liquid correction for paper.
Entries linking to white-out
white adj.
Old English hwit "bright, radiant; clear, fair," also as a noun (see separate entry), from Proto-Germanic *hweit- (source also of Old Saxon and Old Frisian hwit, Old Norse hvitr, Dutch wit, Old High German hwiz, German weiß, Gothic hveits), from PIE *kweid-o-, suffixed form of root *kweit- "white; to shine" (source also of Sanskrit svetah "white;" Old Church Slavonic sviteti "to shine," svetu "light;" Lithuanian šviesti "to shine," švaityti "to brighten").
As a surname, originally with reference to fair hair or complexion, it is one of the oldest in English, being well-established before the Conquest. Meaning "morally pure" was in Old English. Association with royalist causes is late 18c. Slang sense of "honorable, fair" is 1877, American English; in Middle English it meant "gracious, friendly, favorable." The racial sense "of those races (chiefly European or of European extraction) characterized by light complexion" is recorded from c. 1600; meaning "characteristic of or pertaining to white people" is from 1852, American English. White supremacy attested from 1868, American English [John H. Van Evrie, M.D., "White Supremacy and Negro Subordination," New York, 1868]; white flight is from 1966, American English.
White way "brightly illuminated street in a big city" is from 1908. White flag of truce or surrender is from c. 1600. White lie is attested from 1741. White Christmas is attested from 1847. White House as the name of the U.S. presidential residence is recorded from 1811. White water "river rapids" is recorded from 1580s. White Russian "language of Byelorussia" is recorded from 1850; the mixed drink is from c. 1978. Astronomical white dwarf is from 1924. White witch, one who used the power for good, is from 1620s.
out adv.
expressing motion or direction from within or from a central point, also removal from proper place or position, Old English ut "out, without, outside," from Proto-Germanic *ūt- (Old Norse, Old Frisian, Old Saxon, Gothic ut, Middle Dutch uut, Dutch uit, Old High German uz, German aus), from PIE root *uidh- "up, out, up away, on high" (source also of Sanskrit ut "up, out," uttarah "higher, upper, later, northern;" Avestan uz- "up, out," Old Irish ud- "out," Latin usque "all the way to, continuously, without interruption," Greek hysteros "the latter," Russian vy- "out").
Sense of "to a full end, completely, to a conclusion or finish" is from c. 1300. Meaning "so as to be no longer burning or alight; into darkness" is from c. 1400. Of position or situation, "beyond the bounds of, not within," early 15c. Meaning "into public notice" is from 1540s; that of "away from one's place of residence," c. 1600. The political sense of "not in office, removed or ejected from a position" is from c. 1600. Meaning "come into sight, become visible" (of stars, etc.) is by 1610s. In radio communication, a word indicating that the speaker has finished speaking, by 1950.
As a preposition, "out of; from, away from; outside of, beyond; except; without, lacking;" mid-13c., from the adverb.
Meaning "from harmonious relations, into quarreling" (as in to fall out) is from 1520s. Meaning "from one's normal state of mind" (as in put out) is from 1580s; out to lunch "insane" is student slang from 1955. Adjectival phrase out-of-the-way "remote, secluded" is attested from late 15c. Out-of-towner "one not from a certain place" is from 1911. Out of this world "excellent" is from 1938; out of sight "excellent, superior" is from 1891. To (verb) it out "bring to a finish" is from 1580s. Expression from here on out "henceforward" is by 1942. Out upon, expressing abhorrence or reproach, is from early 15c.