"remains of food left from a meal, a table scrap," mid-15c. (from c. 1300 in Anglo-Latin), originally of animal food, but not common until late 16c.; probably cognate with early Dutch ooraete, Low German ort, from or-, privative prefix, + etan "to eat" (from PIE root *ed- "to eat"). Perhaps from an unrecorded Old English word.
late 14c., "dung, excrement, feces; filth, dirt," from Old French ordure "filth, uncleanliness" (12c.), from ord, ort "filthy, dirty, foul," from Latin horridus "dreadful" (see horrid). Related: Ordurous.
c. 1300, odde, "constituting a unit in excess of an even number," from Old Norse oddi "third or additional number," as in odda-maðr "third man, odd man (who gives the casting vote)," odda-tala "odd number." The literal meaning of Old Norse oddi is "point of land, angle" (related via notion of "triangle" to oddr "point of a weapon"); from Proto-Germanic *uzdaz "pointed upward" (source also of Old English ord "point of a weapon, spear, source, beginning," Old Frisian ord "point, place," Dutch oord "place, region," Old High German ort "point, angle," German Ort "place"), from PIE *uzdho- (source also of Lithuanian us-nis "thistle"). None of the other languages, however, shows the Old Norse development from "point" to "third number." Used from late 14c. to indicate a surplus over any given sum.
Sense of "strange, peculiar" first attested 1580s from notion of "odd one out, unpaired one of three" (attested earlier, c. 1400, as "singular" in a positive sense of "renowned, rare, choice"). An odd job "casual, disconnected piece of work" (1728) is so called from notion of "not regular." Odd lot "incomplete or random set" is from 1897. The international order of Odd Fellows began as local social clubs in England, late 18c., with Masonic-type trappings; formally organized 1813 in Manchester, England.
"pertaining to or depending upon the use of right angles," 1570s, from French orthogonal, from orthogone, from Late Latin orthogonius, from Greek orthogonios "right-angled," from ortho- "straight" (see ortho-) + gōnia "angle, corner" (from PIE root *genu- (1) "knee; angle"). Related: Orthogonally; orthogonality.
ancient name of Delos, the island held to be the birthplace of Apollo and Artemis, literally "Quail Island," from Greek ortyx "quail," which perhaps shares a common root with Sanskrit vartika "quail." Related: Ortygian.
by 1815, "belonging to the order Orthoptera;" literally "straight-winged," that is, "having wings that lie straight when folded," from Modern Latin orthopterus, from Greek orthopteros "having straight (upright) wings or feathers," from orthos "straight" (see ortho-) + pteron "wing" (from PIE root *pet- "to rush, to fly"). Orthoptera is the name proposed in 1789 for the order of straight-winged insects, including cockroaches, mantises, grasshoppers, crickets, katydids, and true locusts.