Uses of the subjunctive

Subjunctive as main verb
1. Deliberative subjunctive. This is a subjunctive verb in a rhetorical question. 2. Hortatory. A mild first-person command. 3. Jussive. A mild second- or third-person command or wish. 4. Potential. Tells what may possibly or would hypothetically happen.
 * Quid agamus? - What are we to do?
 * Quo modo celetur tantum scelus? - How should such a great crime be concealed?
 * Vivamus, mea Lesbia, atque amemus - Let us live, my Lesbia, and let us love.
 * Sciatur lex per rem publicam. - Let the law be known throughout the republic.
 * Velisne emere carnem? - Would you like to buy the meat?
 * Putes triginta diēs longum tempus esse. - You may think that thirty days is a long time.
 * Lucium pigeat videre hoc. - It would disgust Lucius to see this.

Conditional subjunctives
A conditional sentence consists of two parts. In English, the clause beginning with "if" is called the protasis, and the clause that begins with "then" is called the apodosis. In Latin, there is no word for "then" in conditional sentences, so the two parts are set apart with just a comma.

Not all conditional sentences contain subjunctives, but the two most common kinds of conditional sentences in Latin that contain subjunctives are:

5. Future less vivid. In this kind of conditional sentence, the verbs are both present subjunctive. They indicate something that might or might not happen in the future. It is called "future less vivid" because it is unclear whether it will or not.

Translate the verb in the protasis as "should verb", and the verb in the apodosis as "would verb":
 * Si iterum coniugem meam videam, eam amplectar. - If I should see my wife again, I would embrace her.

6. Contrary to fact. In this kind of conditional sentence, the verbs are both imperfect subjunctive or both pluperfect subjunctive. When the imperfect is used, it presents a hypothetical situation in the present. When the pluperfect is used, it presents a hypothetical situation in the past.

When the verbs are imperfect, translate the verb in the protasis as "were verbing" and the verb in the apodosis as "would verb":
 * Si illum librum legerem, eo fruerer. - If I were reading that book, I would enjoy it.

When the verbs are pluperfect, translate the verb in the protasis as "had verbed" and the verb in the apodosis as "would have verbed":
 * Si servus melius cantavisset, dominum laetiorem fecisset. - If the slave had sung better, he would have made the master happier.

Subjunctives introduced by "ut" or "ne"
7. Purpose clause. The subjunctive can be used to express the purpose of doing something. Before this kind of clause, "ut" translates as "so that", and "ne" translates as "so that…not".

8. Result clause. Seen with words of degree or extent such as "tam", "tantus", or "adeo" to express a result. NOT seen with "ne". Negative result clauses are simply "ut…non".

9. Fearing clause. A fearing clause starting with "ne" expresses a positive fear that something is happening or will happen. Negative fearing clauses are introduced by "ut".
 * Verebar ne urbs caderet. - I was afraid that the city might  fall.
 * Timet ut medicus adsit. - He is afraid that the doctor may not be here.

Subjunctives introduced by other words
10. Anticipatory clause. An anticipatory clause is a subjunctive clause introduced by dum (while, until), donec (while, until), antequam (before) or priusquam (before). It expresses "until" or "before" the time something might or would happen. Translate a present tense verb in this clause as "should verb", an imperfect as "would verb" and a pluperfect as "would have verbed." 11. Cum clause. There are three types of subjunctive cum clauses: A big hint is that if you see "tamen" in the main clause, then the "cum" clause is concessive. Otherwise, it is best to just translate the sentences and test "when", "since", and "although" as translations for "cum" and seeing which one makes the most sense.
 * Fugimus priusquam vidissemus pugnās. - We fled before we would have seen the fights.
 * Aut moror dum frater Pygmalion destruat moenia mea? - Or do I wait until my brother Pygmalion should destroy my walls?
 * Temporal.  Just expresses what was going on when something occurred. "Cum" translates as "when".
 * Cum dormirem, canis omnem cibum consumpsit. - When I was sleeping, the dog ate all the food.
 * Causal. This time, what is going on in the "cum" clause causes or brings about what is going on in the main clause. "Cum" translates as "since".
 * Cum navissem, valde madidus eram. - Since I had swum, I was very wet.
 * Concessive. This time, what is going on in the "cum" clause goes against or discourages what is going on in the main clause. "Cum" translates as "although".
 * Cum monitus essem, tamen silvam intravi. - Although I had been warned, I entered the forest nonetheless.

12. Relative purpose clause. Expresses purpose, but uses a relative pronoun (qui, quae, quod) in place of the "ut". In this clause, someone or something is somehow used for, or put to, some purpose.
 * Misimus militēs qui tumultūs mollirent. - We sent soldiers who might calm the riots. (i.e. for the purpose of calming the riots.)
 * Emi panem quem consumerem. - I bought bread which I might eat. (i.e. for the purpose of eating.)

13. Relative clause of characteristic. This kind of clause also begins with a relative pronoun. Rather than expressing a purpose, this simply describes someone.
 * Miles qui vulnera fingat turpis est. - A soldier who feigns (would feign) his wounds is shameful.

14. Doubting clause. A doubting clause starts with "quin" after, well, a verb of doubting, and it expresses, well, a doubt. "Quin" just translates as "that" in these kinds of clauses.
 * Dubito quin discipulī bene dormiant. - I doubt that students sleep well.

Optative subjunctive
15. Optative. Expresses a wish that something were happening or had happened. It may or may not be introduced by "si tantum" (if only), "utinam" (if only), or "utinam…ne" (if only not). Unlike the jussive and hortatory, which are almost always present tense, the optative is usually pluperfect or imperfect.
 * Eadem me ad fata vocasses. - You should have called me to the same fate.
 * Utinam ne aegrotarem. - If only I were not sick.