英语词源字典 - 在线词源网站

octa-[octa- 词源字典]: before vowels oct-, word-forming element meaning "eight," from Greek okta-, okt-, from PIE *okto(u) "eight" (see eight). The variant form octo- often appears in words taken from Latin, but the Greek form is said to be the more common in English.[octa- etymology, octa- origin, 英语词源]
octagon (n.): 1650s, from Latin octagonos, from Greek oktagononos, literally "eight-angled," from okta- comb. form of okto "eight" (see eight) + gonia "angle," related to gony "knee" (see -gon). Also octogon (1650s), from French octogone.
octagonal (adj.): 1570s, from octagon + -al (1).
octahedron (n.): 1560s, from Greek oktahedron, neuter of oktahedros "eight-sided," from okta- "eight" (see octa-) + hedra "seat" (see sedentary). Related: Octahedral.
octane (n.): hydrocarbon of the methane series, 1872, coined from octo- (see octa-) + -ane; so called because it has eight carbon atoms. A fuel's octane rating, in reference to its anti-knocking quality, is attested from 1932.
octant (n.): instrument for making angular measurements in navigation or astronomy, 1731, from Late Latin octans "the eighth part," from octo "eight" (see octa-) on analogy of quadrant. In geometry, octant meant "the eighth part of a circle."
octave (n.): c. 1300, utaves (plural, via Anglo-French from popular Old French form oitieve, otaves), reformed in early 15c., from Medieval Latin octava, from Latin octava dies "eighth day," fem. of octavus "eighth," from octo (see eight). Originally "period of eight days after a festival," also "eighth day after a festival" (counting both days, by inclusive reckoning, thus if the festival was on a Sunday, the octaves would be the following Sunday). Verse sense of "stanza of eight lines" is from 1580s; musical sense of "note eight diatonic degrees above (or below) a given note" is first recorded 1650s, from Latin octava (pars) "eighth part." Formerly English eighth was used in this sense (mid-15c.)
Octavia: fem. proper name, from Latin, fem. of Octavius, literally "the eighth" (see Octavian).
Octavian: masc. proper name, from Latin, from Octavius, from octavus "eighth," from octo (see eight).
But although we find so marked differences in the use of the numerals as names, it is impossible to believe that this use did not arise in the same way for all; that is, that they were at first used to distinguish children by the order of birth. But when we find them as praenomina in historical times it is evident that they no longer referred to order of birth. [George Davis Chase, "The Origin of Roman Praenomina," "Harvard Studies in Classical Philology," 1897]
octavo (n.): 1580s, printer's word for sheets folded to make eight leaves, from Latin in octavo "in the eighth," ablative of octavus "eighth" (see octave). Abbreviation is 8vo.
octo-: word-forming element, before vowels oct-, from comb. form of Latin octo "eight" (see octa-).
October: c.1050, from Latin October (mensis), from octo "eight," from PIE root *octo(u)- "eight" (see eight). Eighth month of the old Roman calendar (pre-46 B.C.E.), which began the year in March. For -ber see December. Replaced Old English winterfylleð. In Russian history, October Revolution (in which the Bolsheviks overthrew the Provisional Government) happened Nov. 7, but because Russia had not at that time adpoted the Gregorian calendar reform, this date was reckoned there (Old Style) as Oct. 25.
Octobrist (n.): 1., from Russian oktyabrist, "member of the league formed October 1905 in response to imperial policies"; 2., from Russian Oktyabryonok, "member of a Russian communist children's organization founded 1925 and named in honor of the October Revolution."
octogenarian (n.): 1789, with -an + French octogénaire "aged 80," from Latin octogenarius "containing eighty," from octogeni "eighty each," related to octoginta "eighty," from octo "eight" (see eight) + -genaria "ten times," from PIE *dkm-ta-, from *dekm- "ten" (see ten). As an adjective from 1784.
octopod: 1826 (adj.); 1835 (n.), from Latinized form of Greek oktopod-, from stem of oktopous (see octopus).
octopus (n.): 1758, genus name of a type of eight-armed cephalopod mollusks, from Greek oktopous, literally "eight-footed," from okto "eight" (see eight) + pous "foot," from PIE root *ped- (1) "a foot" (see foot (n.)). Proper plural is octopodes, though octopuses probably works better in English. Octopi is from mistaken assumption that -us in this word is the Latin noun ending that takes -i in plural.
octoroon (n.): 1861, irregular formation from Latin octo "eight" (see eight) + suffix abstracted from quadroon (in which the suffix actually is -oon). Offspring of a quadroon and a white; so called for having one-eighth Negro blood.
octuple (adj.): "eightfold," c. 1600, from Latin octuplus "eightfgold," from octo "eight" (see octo-) + -plus "-fold" (see plus).
ocular (adj.): c. 1500, from Late Latin ocularis "of the eyes," from Latin oculus "an eye," from PIE root *okw- "to see" (cognates: Gothic augo, Old English eage "eye;" see eye (n.)). As a noun, 1835, from the adjective.
oculist (n.): "eye doctor," 1610s, from French oculiste (16c.), from Latin oculus "an eye" (see eye (n.)).