In AP Latin, cum is a word with two jobs: as a conjunction it introduces a subordinate clause translated "when," "since," or "although" (depending on context), and as a preposition with the ablative it means "with." The conjunction use is tested directly in the CED (AP Latin 5.5.F).
Cum is one of the highest-frequency words in your AP Latin syllabus, and the CED calls it out by name. Under learning objective AP Latin 5.5.F, when cum introduces a clause, it may be translated "when," "since," or "although," among other acceptable translations. That flexibility is the whole point. A cum clause sets up the time or circumstance of the main action, and context decides which English word fits best. Cum with an indicative verb usually just marks time ("when"). Cum with a subjunctive verb can be temporal/circumstantial ("when"), causal ("since"), or concessive ("although"), and concessive cum often gets a helpful tamen ("nevertheless") in the main clause as a signal.
The catch is that cum is also a preposition. Cum + an ablative noun simply means "with" (think cum sociis, "with his companions"). So every time you hit cum, your first move is a quick check. Is there an ablative noun right next to it? Probably the preposition. Is there a verb later in the clause, especially a subjunctive? You're in a cum clause, and you need to pick "when," "since," or "although" based on what the sentence is actually saying.
Cum lives in Unit 5 (Vergil's Aeneid) through Topic 5.5, the Camilla passage from Book 11, where the CED's essential knowledge for AP Latin 5.5.F spells out the acceptable translations. It also feeds directly into AP Latin 5.5.G, translating into idiomatic English. Graders score translation FRQs in chunks called segments, and a cum clause is almost always its own segment. Translate cum + subjunctive as "with," and that segment is gone. Beyond translation, reading cum correctly matters for interpretation (5.5.J and 5.5.L). Whether Vergil means "when Camilla did X" or "although Camilla did X" changes the logic of the sentence and the attitude behind it.
Keep studying AP Latin Unit 5
Ablative Absolute (Unit 5)
The CED pairs these for a reason. An ablative absolute (noun + participle in the ablative) does the same job as a cum clause: it shows the time or circumstance of the main action. In fact, a smooth way to translate many ablative absolutes is to turn them into a cum clause in English, "when/since/although the city had been captured."
Relative Clauses with qui, quae, quod (Unit 5)
Both cum and the relative pronoun introduce subordinate clauses, so the same reading skill applies. Find the clause's boundaries, find its verb, then decide how it hangs off the main sentence. If you can bracket a relative clause, you can bracket a cum clause.
Caesar's Gallic War Prose (Units 1-4)
Caesar leans on cum clauses constantly to structure his narrative. The 2018 short-answer stimulus includes "Plerique, cum aut aere alieno..." right in the passage, so you'll meet cum in the prose half of the syllabus just as often as in Vergil.
Diana and Camilla (Unit 5)
Topic 5.5 is Diana's speech about Camilla in Aeneid 11.532-594, the passage where the CED anchors this cum knowledge. Subordinate clauses carry the backstory of how Camilla came under Diana's protection, so parsing them correctly is how you follow the narrative.
Cum shows up everywhere translation is tested. The literal-translation FRQ regularly includes cum clauses, and released Caesar passages like the 2018 short-answer stimulus ("Plerique, cum aut aere alieno...") put one right in front of you. Scoring is segment-based, so a botched cum clause typically costs you that entire segment. Your job is to (1) decide preposition vs. conjunction, (2) choose "when," "since," or "although" based on context (the CED explicitly accepts multiple translations, so a defensible choice earns credit), and (3) render the verb's tense and mood correctly within the clause. Multiple-choice questions on syntax can also ask you to identify what kind of clause cum introduces or what an underlined cum means in context.
Same four letters, totally different grammar. Preposition cum takes an ablative noun and means "with" (cum amicis, "with friends"). Conjunction cum introduces a whole clause with its own verb and means "when," "since," or "although." Quick test: if cum sits directly before an ablative noun and there's no clause verb attached, it's the preposition. If a verb (especially a subjunctive) follows somewhere in the clause, it's the conjunction. Translating conjunction cum as "with" is one of the most common segment-killers on the translation FRQ.
When cum introduces a clause, the CED says it can be translated "when," "since," or "although," and context determines which one fits.
Cum is also a preposition that takes the ablative and means "with," so always check for an ablative noun versus a clause verb before translating.
Cum + indicative is usually temporal ("when"); cum + subjunctive can be temporal, causal ("since"), or concessive ("although").
A tamen ("nevertheless") in the main clause is a strong signal that the cum clause is concessive and should be translated "although."
Cum clauses and ablative absolutes do the same job, showing the time or circumstance of the main action, and English translations of both often start with "when," "since," or "although."
On the translation FRQ, a cum clause is typically scored as its own segment, so misreading cum costs real points.
It depends on its job in the sentence. As a conjunction introducing a clause, cum means "when," "since," or "although" (the CED lists all three as acceptable under AP Latin 5.5.F). As a preposition with an ablative noun, it means "with."
No. "When" is only one option. With a subjunctive verb, cum can also mean "since" (causal) or "although" (concessive). Picking the translation that matches the sentence's logic is exactly what the exam rewards.
Look at what follows. Cum directly before an ablative noun with no clause attached is the preposition, "with." Cum followed by a clause containing its own verb, especially a subjunctive, is the conjunction, "when/since/although."
Read the relationship between the clauses. If the cum clause gives a reason for the main action, use "since." If it sets up a contrast (often flagged by tamen in the main clause), use "although." If it just marks time, use "when."
Yes, constantly. The CED names it in the essential knowledge for Topic 5.5 (AP Latin 5.5.F), and released exam passages, like the 2018 short-answer Caesar stimulus with "Plerique, cum aut aere alieno...," include cum clauses you have to read correctly to translate or analyze.