ole-o: oil; -oza, -atra: oleaginous; -izar: to oil (ulo); -ifar: to produce oil, give out oil; -uyo: oil-holder, oilcan; cruet; -lampo: Argand lamp: common oil lamp for illumination; -farbo: oil paint; -i santa: (eccl.) holy oils; brul- -o: lamp-oil, kerosene; ricin- -o: castor oil; oliv- -o: olive-oil. — DEFIS
olfakt-ar*: (tr.) to perceiveby sense of smell; -o: olfaction. -ala organo: olfactory organ. — EFIS
oliban-o: olibanum: frankincense. — eFIS
oligark-o*: oligarch. — DEFIRS
oligarki-o: oligarchy. — DEFIRS
oligocen-o: (geol.) oligocene. — DEFIS
olim: formerly, in former times, once upon a time; -a: former; -a tempo: in days of old. Ex.: Olim esis kustumo. La homi di olima tempo. Olim ula princo regnis. Olima kustumo. — L
Olimp-o*: Olympus; -ano: a dweller in Olympus.
olimpiad-o: Olympiad: a period of four years. — DEFIRS
oliv-o: (fruit) olive; -iero: olive tree. — DEFIRS
ombr-o: shadow, shade; -izar: to shade, over shade; put in, cover with shadows; -oza, -iz-anta: shadowy, shady, umbrageous. — eFIS
oment-o*: (anat.) omentum. — DEFIRS
omis-ar*: (tr.) to omit, leave out or undone, pass over; -o, -ajo: omission (cf. neglijar). Ex.: Omisar formalajo. Ne omisez facar to. Il omisis fakto importanta. — EFIS
omlet-o: omelet. — DEFR
omn-a: (collective sense) all, every; -i: all, everybody (collect.) -o: everything; -u: every one; omna tri, omna quar: all three, all four; il havas du filiuli, qui omna esas soldati: he has two sons who are (both) soldiers; de omna loki: from every place; -a-di-e, -a: daily, every day; -o-fac-anto: factotum; -a-kaze: in any case, in any event; -a-foye: every time; -a-loke: every place; -o-manj-anta: omnivorous (cf. omnivora); -a-monata, -e: every month, monthly; -a-maniere: in every way; -o-povo: omnipotence; -o-pov-anta: omnipotent, all powerful; -o-savo: omniscience; -o-sav-anta: omniscient; -a-semen-a, -e: weekly, every week. -o-sufr-anto: (fig.) drudge; -a-sorta, -speca: every kind of; -o-tush-ero: (fig.) meddler, busy-body; -ube: wherever. V. exp.: vid. singla. — eIL
omnibus-o: (vehicle) omnibus. — DEFIRS
omnivor-o: ominvorous. — DEFIS
on: one (indefinite pronoun): people, men, we, they (when used vaguely for society), for people in general; on dicas: people say, they say; on devas amar sua gepatri: we should love our parents; on ne povas manjar sua kuko e konservar oclass="underline" you cannot eat your cake and have it. (Note: Ni translates «we» only when a limited number of persons is thought of with whom the speaker or writer is directly associated: ni qui kredas ke I.L. esas posibla). — EF
onagr-o*: (zool.) onager: a wild ass (Equus Onager); (hist.) onager: a stone-throwing machine. — DEFIS
omani-ar*: (intr.) to masturbate; -(ad)o: masturbation, onanism. — DEFIRS
ond-o: (lit. and fig.) (small) wave, swell, surge (of water); undulation; -ego: billow, breaker; -ifar: to rise in billow form or produce waves; to undulate, wave; -igar, -izar: to cause waves on; to cover with waves; -ifo, -aro: undulation, waves; -oza, -atra, -ifanta, -izita: wavy, wavelike, undulating; -agit-ata: rough; -agit-eso: billowy. Ex.: Ondi di maro, di soni, di tero (sismala). La maro ondifas. La vento ond-igas, -izas la maro. Ondoza surfaco. — EFIS
onix-o: (min.) onyx. — DEFIRS
onkl-(ul)o: uncle; -ino: aunt; -ala: avuncular; pre-onkl-ulo: great-uncle. — DEF
onomatope-o: (gram.) onomatopoeia. — DEFIS
ontogenez-o*: (biol.) ontogenesis. — DEFIS
ontologi-o: (philos.) ontology. — DEFIRS
onyon-o: (plant and edible bulb) onion; -eyo: onion-bed; -shelo: onion-skin, -peel. — EF
oolit-o: (geol.) oolite. — DEFIRS
opak-a: opaque. Def.: Qua ne esas diafana, ne permeebla per lumo. Ant.: diafana, translucida. — DEFIS
opal-o: (min.) opal; -vitro: (fig.) opal (or, iridescent) glass. — DEFIRS
opalec-ar*: (intr.) to opalesce. — DEFIS
oper-o: opera; -eto: operetta; -o-teatro: opera house. — DEFIRS
operac-ar: (tr., surg., mil., math., finan.) to operate (upon); -ato, -ito: person operated upon; -ar malado, tumoro: to operate upon a sick person, a tumor. Ex.: Subisar operaco. Financalo operaco. Operaco en sustraciono. Militala operaco. — DEFIRS
operkul-o: (bot., anat., zool.) operculum (cover, lid). — EFIS
opiat-o: (med.) opiate. — DEFIS
opinion-ar: (tr.) to opine, express one’s opinion, be of the opinion. Def.: Expresar judiko pri temo. Ex.: Me favore opinionas pri la projeto. Publika opiniono. — EFIS
opium-o: opium; -oza: containing opium. — DEFIRS
opodeldok-o*: (med.) opodeldoc. — DEFI
oport-ar, -as: (intr., impersonal) it is required, it is necessary (ke); (cf. suffix: -end-); oportas levar ni fru morge: it is necessary to get up early to-morrow. V. exp.: Kande ica signifiko havas subjekto, on uzas mustar: oportas ke vu departez: vu mustas departar. — L
oportun-a: (of things) opportune, seasonable, timely, convenient (cf. favor-oza); -eso: opportuneness (cf. okaziono); -ismo: (politics) opportunism; -isto: opportunist; (N.B. «opportunity» is translated by okaziono or oportunajo); Ex.: Okaziono oportuna. Oportuneso di la sokurso. — DEFIS