Etymology
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security (n.)
mid-15c., "condition of being secure," from Latin securitas, from securus "free from care" (see secure). Replacing sikerte (early 15c.), from an earlier borrowing from Latin; earlier in the sense "security" was sikerhede (early 13c.); sikernesse (c. 1200).

Meaning "something which secures" is from 1580s; "safety of a state, person, etc." is from 1941. Legal sense of "property in bonds" is from mid-15c.; that of "document held by a creditor" is from 1680s. Phrase security blanket in figurative sense is attested from 1966, in reference to the crib blanket carried by the character Linus in the "Peanuts" comic strip (1956).
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measure (n.)

c. 1200, "moderation, temperance, abstemiousness;" c. 1300, "instrument for measuring," from Old French mesure "limit, boundary; quantity, dimension; occasion, time" (12c.), from Latin mensura "a measuring, a measurement; thing to measure by," from mensus, past participle of metiri "to measure," from PIE root *me- (2) "to measure." The native word was Old English cognate mæð "measure."

Meaning "size or quantity as ascertained by measuring" is from early 14c. Meanings "action of measuring; standard measure of quantity; system of measuring; appointed or allotted amount of anything" are from late 14c. Also from late 14c. are the senses "proper proportion; balance." Sense of "that to which something is compared to determine its quantity" is from 1570s.

In music, from late 14c. as "air, tune;" 1570s as "rhythmic pattern." Specifically as "a group of tones indicated between two primary beats" is from 1660s. From mid-15c. as "rhythmic pattern in poetry;" c. 1500 in dance. Meaning "treatment 'meted out' to someone" is from 1590s; that of "plan or course of action intended to obtain some goal" is from 1690s; sense of "legislative enactment" is from 1759. Figurative phrase for good measure is from good measure as "ample in quantity in goods sold by measure" (late 14c.).

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measure (v.)

early 14c., mesuren, "to exercise moderation;" mid-14c., "to deal out or divide up by measure," also "to ascertain spatial dimensions, quantity, or capacity of by comparison with a standard;" from Old French mesurer "measure; moderate, curb" (12c.), from Late Latin mensurare "to measure," from Latin mensura "a measuring, a measurement; thing to measure by," from mensus, past participle of metiri "to measure," from PIE root *me- (2) "to measure." The native verb is mete. Intransitive sense of "to be of a (specified) measure" is from 1670s. To measure up "have the necessary abilities" is 1910, American English. Related: Measured; measuring.

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half-measure (n.)
"incomplete effort," 1798, from half + measure (n.).
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Shin Bet (n.)
Israeli security service, 1964, from Modern Hebrew shin + bet, names of the initial letters of sherut bitahon (kelali) "(general) security service."
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KGB 
national security agency of the Soviet Union from 1954 to 1991, attested from 1955 in English, initialism (acronym) of Russian Komitet gosudarstvennoy bezopasnosti "Committee for State Security."
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gage (v.)
c. 1400, "to deposit as security," from Old French gager, gagier "to guarantee, promise, pledge, swear; bet, wager; pay," from gage "security, pledge" (see gage (n.)). Related: Gaged; gaging. For the measuring sense, see gauge (v.).
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mensural (adj.)

c. 1600, in music, "having a fixed measure;" 1650s, "pertaining to measure, measurable," from Medieval Latin mensuralis, from Latin mensura "a measuring, a measurement; thing to measure by," from mensus, past participle of metiri "to measure," from PIE root *me- (2) "to measure."

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collateral (n.)

"colleague, associate," 1510s, from collateral (adj.). Meaning "something of value given as security" is from 1832, American English, from phrase collateral security "property, etc., given to secure the performance of a contract" (1720), in which collateral (adj.) has the sense of "aiding or confirming in a secondary way."

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remeasure (v.)

also re-measure, "to measure again or anew," 1580s, from re- "again" + measure (v.). Related: Remeasured; remeasuring; remeasurement.

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