This table was compiled from multiple sources on the Internet; in other words, it's guaranteed to be inaccurate. Caveat lector!
| O curas hominum! O quantum est in rebus inane! | Ah, human cares! Ah, how much futility in the world! (Lucilius) |
| O di immortales! | Good heavens! (uttered by Cicero on the Senate floor) |
| O diem praeclarum! | Oh, what a beautiful day! |
| O praeclarum custodem ovium lupum! | An excellent protector of sheep, the wolf! (Cicero) |
| O quam cito transit gloria mundi! | O how quickly passes the glory of the world! |
| O sancta simplicitas! | Oh, holy simplicity! (Jan Hus) |
| O tempora, O mores! | Oh the times! Oh the morals! (Marcus Tullius Cicero, Catilina I, 1, 2) also translated "Oh the times! Oh the customs!". |
| O! Plus! Perge! Aio! Hui! Hem! | Oh! More! Go on! Yes! Ooh! Ummm! |
| Obesa cantavit | The fat lady has sung |
| Obiit (Ob.) | He/she died |
| Obiter (Ob.) | In passing |
| Obiter dictum | Something said in passing. Parenthetical remark. |
| Oblitus sum perpolire clepsydras! | I forgot to polish the clocks! |
| Obscurum per obscurius | The obscure by means of the more obscure |
| Observa quo vadis, cinaede! | Watch where you're going, you jerk! |
| Obsta principiis | Resist the beginnings. Nip it in the bud. |
| Occasio aegre offertur, facile amittitur | Opportunity is offered with difficulty, lost with ease. (Publius Syrus) |
| Occasio facit furem | Opportunity makes a thief |
| Occasus ejus praemium suum est | Decadence is its own reward |
| Oculi sunt in amore duces | The eyes are leaders in love |
| Oculus dexter (O.D.) | Right eye (ophthalmologist shorthand) |
| Oculus sinister (O.S.) | Left eye (ophthalmologist shorthand) |
| Oderint dum metuant | Let them hate provided that they fear. (Seneca) |
| Odi brassicum | I hate broccoli |
| Odi et amo | I hate (her), and I love (her) -- from Catullus. |
| Odi et amo, quare id facere forasse requiris...Nescio, sed fieri sentio et excrucior | I hated and I love, perhaps you ask why I do it...I don't know, but I feel it and I'm tortured. |
| Odium theologicum | Theological hatred -- a name for the special hatred generated in theological disputes. |
| Olevm addere camino | To pour fuel on the stove adding gasoline to a fire |
| Olevm perdisti | You have lost oil you've wasted your time on this criticism for a misallocation of resources |
| Olim | Formerly |
| Olim habeas eorum pecuniam, numquam eam reddis: prima regula quaesitus | Once you have their money, you never give it back: the 1st rule of acquisiton |
| Omnai dubita | Doubt everything |
| Omne ignotum pro magnifico | All that is unknown appears magnificent. |
| Omne initium est difficile | Every beginning is difficult |
| Omne trium perfectum | Everything that comes in threes is perfect |
| Omne tulit punctum qui miscuit utile dulci | He has gained every point who has combined [the] useful [with the] agreeable. |
| Omnes aequo animo parent ubi digni imperant | All men cheerfully obey where worthy men rule. (Syrus) |
| Omnes deteriores svmvs licentia | Too much freedom debases us |
| Omnes lagani pistrinae gelate male sapiunt | All frozen pizzas taste lousy |
| Omnes una manet nox | The same night awaits us all. (Horace) |
| Omnes vulnerant, ultima necat | All (hours) wound, the last kills. (inscription on solar clocks) |
| Omnia dicta fortiora, si dicta latina | Everything sounds more impressive when said in Latin -- Mostly used as a form of irony to poke fun at people who seem to use Latin phrases and quotes only to make themselves sound more important or "educated". |
| Omnia iam fient quae posse negabam | Everything which I used to say could not happen will happen now. (Ovid) |
| Omnia mea mecum porto | All that is mine, I carry with me. (My wisdom is my greatest wealth) (Cicero) |
| Omnia mihi lingua graeca sunt | It's all Greek to me |
| Omnia mors aequat | Death equals all things |
| Omnia munda mundis | Everything is pure to pure ones |
| Omnia mutantur nos et mutamur in illis | All things change, and we change with them |
| Omnia mutantur, nihil interit | Everything changes, nothing perishes. (Ovid) |
| Omnia mutantur, nos et mutamur in illis | All things are changing, and we are changing with them |
| Omnia omnibus | To be all things to all |
| Omnia vincit amor; et nos cedamus amori | Love conquers all things; let us too surrender to love. (Vergil) |
| Omnis potestas a Deo est | All power is from God |
| Omnium gatherum | Assortment |
| Omnium rerum principia parva sunt | Everything has a small beginning. (Cicero) |
| Onus probandi | The burden of proof |
| Opera omnia | All works -- the collected works of some author. |
| Opera posthuma | Posthumous works -- i.e., published after the author's death. |
| Opere citato (op. cit.) | In work (already) cited -- used in academic works when referring again to the last source mentioned or used. |
| Ophidia in herba | A snake in the grass -- any hidden danger or unknown risk. |
| Opinio juris sive necessitatis | The perception that a given behavior is required by law, that it is legally obliged, a duty; as opposed to behaviors that are motivated by other concerns, or simply random or habitual behavior. Example: the S.S. Lotus case. Oftern trincated to "opinio juris." |
| Optima semper | The best always |
| Optimis parentibus | To my excellent parents. A common dedication in a book |
| Optimus magister, bonus liber | The best teacher is a good book |
| Opus dei | The work of God |
| Ora et labora | Pray and work. (St. Benedict) |
| Ora pro nobis | Pray for us |
| Oratvr fit, poeta nascitvr | An orator is made [but] a poet is born |
| Orbes volantes exstare | Flying saucers are real |
| Orbiter dictum/dicta | Said by the way (miscellaneous remarks) |
| Orcae ita | Pretty straightforward |
| Orden Pour le Mérite | Order for the Merit |
| Ore rotundo | With full voice |
| Osculare pultem meam! | Kiss my grits! |
| Otium sine litteris mors est | Leisure without literature is death |
