Decimate

Decimate (pronounced des-uh-meyt)

(1) To destroy a great number or proportion of; to devastate, to reduce or destroy significantly but not completely (modern use).

(2) To select by lot and kill every tenth person (obsolete except for historic references).

(3) To take a tenth of or from (obsolete except for historic references).

(4) In computer graphics processing, to replace something rendered in high-resolution with something of lower but still acceptable quality.

(5) To exact a tithe or other 10% tax (almost archaic except in the internal rules of some religions).

1590–1600: From the Latin decimātus (tithing area; tithing rights), past participle of decimāre (to punish every tenth man chosen by lot) a verbal derivative of decimus (tenth), a derivative of decem (ten) and decimo (take a tenth), from the primitive Indo-European root dekm (ten).  The related nouns are decimation & decimator, the verbs (used with object) are decimated & decimating.  The most commonly used synonyms now are: wipe out, obliterate, annihilate, slaughter, exterminate, execute, massacre, butcher, stamp out & kill off

Decimate is interesting as an example of two linguistic phenomena.

(1) It’s a foreign word (Latin) which has become part of the English language.  This happens a lot (eg fuselage) because English is a vacuum-cleaner language which sucks in whatever is needed but it’s not universal and there’s no precise rule which decides what become assimilated and what, however frequently used, remains foreign: zeitgeist (spirit of the age) although now common in English, remains German.

(2) It’s a contranym, a word which in modern use, now means the opposite of its classical origins.  In Roman times, it meant to reduce by 10%; now it’s probably understood to reduce to, if not 10% then a least by a large portion.  This is a genuine meaning shift and, except in precise historic references (and then probably foot-noted), the new meaning is now correct.  Decimate thus differs from a word like enormity; if used (as it sometimes is) to mean enormous that’s not an error because by virtue of use, that meaning has been absorbed into the language as a concurrent use with the original.  By contrast, decimate has suffered a meaning shift.

The killing of one in ten, chosen by lots, from a rebellious city or a mutinous army was a punishment sometimes used by the Romans and there have been many instances of it (expressed usually as collective punishment) since, Adolf Hitler (1889-1945; Führer (leader) and German head of government 1933-1945 & head of state 1934-1945) explicitly referring to the Roman tradition when in 1934 explaining why there had been so many (retrospectively authorized) executions during the suppression of the so-called "Röhm putsch" (the Führer's actions now sometimes (generously) described as a pre-emptive or preventative strike).  The word has been (loosely and un-etymologically) used since as early as the 1660s to mean "destroy a large but indefinite number of."  This is one of those things which really annoys pedants but given it’s been happening since the seventeenth century, it may be time for them to admit defeat.  Were the word now to be used to convey its original meaning, the result would probably be only confusion.  One point in use which is important is that one should speak of the whole of something being decimated, not a part (eg a plague decimated the population, not disease decimated most of the population).  Decimate remains well-known because is well known because it’s lived on in Modern English, albeit with quite some mission-creep in meaning but the Romans had many other expressions defining the precise proportionality of a reduction by single aliquot part including: tertiate (⅓), quintate (⅕), sextate (⅙), septimate (⅐), duodecimate (¹⁄₁₂) and centesimate (¹⁄₁₀₀).

Smaller but not decimated: Lindsay Lohan full-sized (left), reduced by 10% (centre) & reduced by 90% (right).

However, although most probably now understood what is meant by decimate even if they're unaware of the word's origin, it should still be use with some care.  Sir Ernest Gowers (1880–1966) in his revision (1965) of Henry Fowler's  (1858–1933) A Dictionary of Modern English Usage (1926) objected to the "virtual extermination" of rabbits by the agent of the myxomatosis virus being described as a decimation because, with a reported death rate of 99.8%, it was something notably more severe than modern understanding of the word let alone that of a Roman.  In the way of such things the rabbits anyway staged a revival as natural selection did its thing.  Fowler's guide also cautioned that any use "expressly inconsistent with the proper sense... must be avoided", citing "A single frost night decimated the currants by as much as 80%".  The point is taken but that sentence does seem helpfully informative.  Nor are all acts of reduction of necessity instances of decimation; there has to be something destructive about the process.  A photograph can be reduced in size by a Roman 10% or a modern 90% but one wouldn't suggest it has been decimated; it has just be rendered smaller.