"computer operating system using a disk storage device," 1967, acronym of disk operating system.
a line or hooked line used to separate printed figures, originally with numerals and used where modern texts use a decimal point, 1650s, from Late Latin (linea) separatrix, feminine of separator, agent noun from separare "to pull apart" (see separate (v.)). It survives in proofreading.
1680s, from Latin sext-, combining form of sex "six" (see six) + ending from million. Compare billion. In English, and originally Italian, numeration, 1 to the 6th power (one followed by thirty-six zeroes); in French and U.S. use, 1,000 to the 7th power (one followed by twenty-one zeroes). Related: Sextillionth.
"pertaining to the system of weights and measures based on the meter," 1855, from French métrique, from mèter (see meter (n.2)). In this sense, metrical is attested from 1797. Metric system is attested by 1855.