- oeuvre[oeuvre 词源字典]
- oeuvre: hors d’oeuvre  In French, hors d’oeuvre means literally ‘outside the work’ – that is, ‘not part of the ordinary set of courses in a meal’. The earliest record of its use in English is in the general sense ‘out of the ordinary’ (‘The Frenzy of one who is given up for a Lunatick, is a Frenzy hors d’ oeuvre … something which is singular in its kind’, Joseph Addison, Spectator 1714), but this did not survive beyond the 18th century.
Alexander Pope, in his Dunciad 1742, was the first to use the word in its modern culinary sense. (French oeuvre ‘work’, incidentally, comes from Latin opera ‘work’, source of or related to English copious, manoeuvre, opera, operate, and opulent.)
=> d'oeuvre, copious, manoeuvre, manure, opera, operate, opulent[oeuvre etymology, oeuvre origin, 英语词源]
- oaf: see elf
- oak: [OE] Oak is an ancient Germanic tree-name, shared by German (eiche), Dutch (eik), Swedish (ek), and Danish (eg). These point back to a common Germanic ancestor *aiks. There is no conclusive evidence of any related forms outside Germanic, however, although similarities have been noted with Greek aigílops, a term for a sort of oak tree, and Latin aesculus ‘oak sacred to Jupiter’.
Despite its passing similarity, acorn is not etymologically related. The oak was one of the commonest trees in the ancient European forests, and many terms that started out as names for it became generalized to simply ‘tree’: English tree, for instance, comes from an Indo-European ancestor that probably originally meant ‘oak’.
- oar: [OE] Oar is a general northern Germanic term, traceable back to an ancestral *airō, source also of Swedish år, Danish aare, and, by borrowing, Finnish airo. It is not clear where it comes from, although it may ultimately be related to Latin rēmus ‘oar’ (as in trirēmis, source of English trireme ).
- oasis:  The ultimate origins of the word oasis no doubt lie in North Africa, and although no positive link has been established, it is likely to be related in some way to Coptic ouahe. This means literally ‘dwelling area’ (it is derived from the verb ouih ‘dwell’), but since isolated fertile spots in the desert are natural centres of habitation, it is used also for ‘oasis’. The farthest back we can actually trace English oasis is, via Latin, to Greek óasis.
- oasthouse:  Although the compound oasthouse is not recorded until the mid 18th century, oast itself, which means ‘kiln’, goes right back to Old English, and beyond, to Indo- European *aidh- ‘burn’. This was also the source of Latin aestās ‘summer’, etymologically the ‘hot season’, from which are descended French été ‘summer’ and English aestivate . Originally oast was simply a general term for ‘kiln’, and the specific application to a ‘hopdrying kiln’ did not begin to emerge until the 16th century.
- obese: see eat
- obey:  ‘To hear is to obey’ carries more than a germ of etymological truth. For obey comes via Old French obeir from Latin ōbēdīre, which meant literally ‘listen to’. It was a compound verb formed from the prefix ob- ‘to’ and audīre ‘hear’ (source of English audible). By classical times the metaphorical sense ‘obey’ had virtually taken over from the original ‘listen to’, and it is this sense that informs the related obedient  and obeisance .
=> audible, obedient
- obfuscate: see dusk
- obituary:  Obituary goes back ultimately to a Latin euphemism for ‘die’, meaning literally ‘go down, make an exit’. This was obīre, a compound verb formed from the prefix ob- ‘down’ and īre ‘go’. From it was derived obitus ‘death’, which formed the basis of the medieval Latin adjective obituārius ‘of death’, source of English obituary. A parallel Latin formation was the adverb obiter ‘on the way, in passing along’, based on the noun iter ‘journey’ (a relative of īre and source of English itinerant  and itinerary ). English preserves it in obiter dictum , literally a ‘statement in passing’.
- object: Object the noun  and object the verb  have diverged considerably over the centuries, but they come from the same ultimate source: Latin obicere. This was a compound verb formed from the prefix ob- ‘towards’ and jacere ‘throw’ (source of English ejaculate, inject, subject, etc), and hence originally meant literally ‘throw towards’, but by classical times it had been extended metaphorically to ‘place a hindrance in the way of, oppose’.
This was the strand of the word’s meaning taken up by English in the verb object, and also originally in the noun (‘how Christ answered to objects [that is, objections] of false Jews’, John Wycliffe 1380). The standard present-day meaning of the noun, however, comes from a post-classical meaning of Latin objectum (the noun formed from the past participle of obicere): ‘something put in someone’s way so that it can be seen’, hence a ‘visible object’.
=> ejaculate, inject, jet, subject
- objurgate: see just
- oblation: see offer
- oblige:  To oblige someone is etymologically to ‘bind them to’ something with a promise. The word comes via Old French obliger from Latin obligāre, a compound verb formed from the prefix ob- ‘to’ and ligāre ‘tie’ (source of English liable, ligament, etc). By classical times its original literal sense had been extended figuratively to ‘make liable, put under an obligation’. The synonymous obligate  comes from its past participial stem, as does obligatory .
=> liable, ligament, obligatory
- obliterate: see letter
- obnoxious: see noxious
- oboe:  The oboe gets its name from its high pitch. Its ultimate ancestor was French hautbois, a compound of haut ‘high’ and bois ‘wood’ (the oboe is a woodwind instrument). English acquired this in the 16th century as hautboy, but from the 18th century it was gradually ousted by the Italian version of the word, oboe (itself originally an acquisition from French).
- obscure: see sky
- obsequious: see sequence
- observe:  Latin observāre meant ‘watch, pay attention to, look to, comply with’. It was a compound verb, formed with the prefix ob- ‘to’ from servāre ‘keep safe’, hence ‘guard, watch, heed’ (no relation to servīre, source of English serve and servant). The two semantic strands ‘seeing, noting’ and ‘complying’ have remained together in the English verb, but have diverged in its derived nouns, the former going to observation , the latter to observance .
=> conserve, reserve