All the Latin in The Raven Cycle that isn’t translated in the books. The page numbers are from the English paperbacks of the first three, and the hardcover of TRK.

with commentary, you don’t have to read that

THE RAVEN BOYS

114 internec-. Whelk was interrupted writing the word on the board, but it's a word for "kill," internecare, with the ending off, so it could be conjugated.

115 Ostendes tuum et ostendam meus? Show my yours and I'll show you mine. ("Meus" is nominative, and here the accusative, "meum" should be used.)

247 Loquere tu nobis? You speak to us? (Loquere is the unconjugated word, here it would be more correct to say "Loquitis nobis?")

249 Hic gaudemus. Gratias tibi ... loquere -- loqui pro nobis. This makes us rejoice. Thank you ... To speak -- you speak for us. (The first literally means "This we rejoice," but I think that's a correct way to say it. In the last bit, "loqui" isn't a word, but I think Gansey means "loquitis.")

THE DREAM THIEVES

81 Ronan Lynch, Greywaren, tu es Greywaren. Ronan Lynch, Greywaren, you are Greywaren.

121 In indiget homo battery. The man needs a battery. (Latin doesn't use the words "a" or "the" so this could also be translated as "A man needs the battery" or whatever. I have no idea what the word "in" is doing here, so we'll blame that on Ronan's bad grammar.)

128 Occidet sum! Kill him! (This is terrible grammar. Literally this means "I am he/she/it kills." "Kill him" would be "Occidet eum." edit: apparently this has been fixed in later editions and now reads “Occidet eum.” I assume then this was a typo rather than more wacky TRC Latin grammatical nonsense.)

129 Ronan, imploro te! Ronan, I beg you! (Perfect grammar.)

230 Scio quid hoc est. I know what this is. (Point of interest: the word for "this" is in the neuter case so whatever it's describing would also have to be a neuter word.

231 Scio quid estis vos. I know what you are. (Latin does not have the tu/vous familiar/formal thing like French, German, Russian or other languages later develop, so this means "I know what you (plural) are," but considering it is Adam saying this right after turning from being Kavinsky, it could mean Adam knows they are both dreamers, rather than being a mistake.)

322 Unum. Amabo te. One. Please. (While this is what it means, there are more common words for "please," and instead this is used throughout the rest of the series. According to this site, this translation means "I would be delighted (if)," or literally "I will love you (if)," so that's interesting.) 

BLUE LILY, LILY BLUE

15 Avide audimus. We listen eagerly. (This could mean "we hear eagerly" as audire most often means "hear" but "listen" makes more sense.)

18 Greywaren semper est incorruptus. The Greywaren is always uncorrupted. 

25 Est aliquid in foramen . . . . Apis? Apibus? Forsitan. Something is in the hole . . . . A bee? To the bees? Perhaps? (I think the "to the bees" is just a bad attempt to pluralize bees so probably this should be in the nominative rather than the ablative or dative, and thus be "Apes?")

83 Solvitur ambulando. It is solved by walking. (This apparently just means that the problem should be solved by practical means.)

84 Quod nomen est tibi. What is your name. (Literally "which name is yours.")

310 Rogo aliquem aliquid. I ask something something. (This doesn't translate awesomely but in more natural English it's "I ask something to something.")

THE RAVEN KING

10 Owynus dei gratia Princeps Waliae . . . Owen by the grace of God the Chief of Wales.

35 Periculosum . . . . Suscitat . . . . Quid--. It is dangerous . . . . It awakens . . . . What-- (The second "it" could also be "he" or "she.")

58 Salve. Hello

72 Cabeswater, dissolvere. Cabsewater, dissolve. (Technically "to dissolve" as the infinitive is used, but this makes more sense.)

74 Operae pretium est. It is worthwhile. (This is not a literal translation but this is what the phrase means.)

157 Fiat lux. Let there be light. (Literally "let light.")

221 Miseria fortes viros, Ronan. Misery tests strong men, Ronan. (“I think that Miseria fortes viros is half of the Seneca quote “Ignis aurum probat – miseria fortes viros” which translates roughly as "Fire tests gold; adversity, of strong men" So the translation is "adversity/misery tests strong men" in that context. Probably Adam was referencing the quote and they learned it at some point in latin class.” thanks to @mysticalspiders for sorting out there what the verb is and that it was a reference.)

284 Unguibus et rostro. With claws and beak. (I have a post about it here if you want to see why it doesn't translate as just "claw and beak," and someone’s helpfully corrected my grammar.)

328 amae vias . . . . Oce iteres. Lay lines . . . . Swiftly you would repeat. (I don't even know what's going on with the grammar here. "Amae" if you look it up will probably be translated as "love" but -ae is not a verb ending so it can't be. It also means "buckets." "Vias" is "paths." From Artemus and Blue's conversation earlier, he references the "amae vias" and it seems, from context, to mean "lay line" rather than "buckets paths." Maybe it's the dream/tree language, rather than Latin, because in Latin this makes no sense and it's established that the dream language resembles to Latin. -es in "iteres" is not a noun ending, so I have no idea what that means exactly so the translation there is a guess.)

382 Vox et praeterea nihil. The voice and nothing more.

394 Forsan et haec olim meminisse juvabit. Maybe someday you will rejoice to recall even this. (This is a line from the Aeneid, when Aeneas addresses his exhausted, shipwrecked companions.)

bonus:

201 (TRK) N'y a pas de quoi fouetter un chat. There's nothing to get worked up about. (Literally, this means "there is nothing for which to whip a cat." It’s in French.)