Etymology
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reserve (v.)

mid-14c., "keep back or in store for future use;" late 14c., "keep as one's own," from Old French reserver "set aside, withhold" (12c.) and directly from Latin reservare "keep back, save up; retain, preserve," from re- "back" (see re-) + servare "to keep, save, preserve, protect" (from PIE root *ser- (1) "to protect"). Meaning "to book" is from 1935. Related: Reserved; reserving.

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hidden (adj.)

past-participle adjective from hide (v.1); a Middle English formation (Old English had gehydd "hidden") on the model of ride/ridden, etc. As "secret, occult" from 1540s. Hidden persuaders (1957) was Vance Packard's term for ad men.

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reserve (n.)

1610s, "something stored up," from reserve (v.) or from French réserve, a back-formation from reserver "set aside, withhold," from Latin reservare "keep back, save up; retain, preserve," from re- "back" (see re-) + servare "to keep, save, preserve, protect" (from PIE root *ser- (1) "to protect").

Meaning "self-imposed restraint on freedom of words or actions; habit of keeping back the feelings" is from 1650s. The meaning "district or place set apart for some particular use" is by 1805. The sense of "amount of capital kept on hand to meet probable expenses or demand" is by 1866. That of "amount of natural resources known to exist in a particular region" is by 1912. As an adjective, "kept in reserve," by 1719.

The military sense of "body of troops withheld from action to serve as reinforcements, etc." is from 1640s; that of "national emergency defense or auxiliary military force" (reserves) is by 1866.

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subsidiary (adj.)

1540s, from Latin subsidiarius "belonging to a reserve, of a reserve, reserved; serving to assist or supplement," from subsidium "a help, aid, relief, troops in reserve" (see subsidy). As a noun, c. 1600, "subsidiary thing." In Latin the word was used as a noun meaning "the reserve."

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free-spoken (adj.)

"accustomed to speaking without reserve," 1620s, from free (adj.) + -spoken.

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backup (n.)

"a standby, a reserve," 1952; see back up (v.). Specific reference to computing is from 1965.

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reservist (n.)

"soldier who belongs to the reserves," 1872, from French réserviste, from reserver (see reserve (v.)).

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cryptic (adj.)

1630s, "hidden, occult, mystical," from Late Latin crypticus, from Greek kryptikos "fit for concealing," from kryptos "hidden" (see crypt). Meaning "mysterious, enigmatic" is attested by 1920. Related: Cryptically.

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cryptonym (n.)

"private, secret, or hidden name," 1868 (by 1855 in German); from crypto- "secret, hidden" + -onym "name," from Greek (from PIE root *no-men-"name").

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