Historically, the word decimate refers to the practice in the Roman army of killing every tenth man in a mutinous unit in order to ensure loyalty of the rest. T surviving 90%. Although the Latin word for ‘tenth’ is embedded in decimate (compare decimal, decimetre etc), t he word is now generally accepted by all but the most historically minded as meaning ‘kill or destroy a large number or part of something’, but should not be used: The famine decimated the population; The industry has been decimated. It goes against the grain of the word, however, to link it with a specific quantity (decimate by 50%), to apply it to an individual or indivisible thing, or to use it as a substitute for annihilate or exterminate