Giving direct commands is essentially a second person phenomenon — someone tells you to do something. In English, imperative mood is the infinitive without the usual “to.” Also, the form doesn't vary between giving an order to one person or to many. To make the command negative, you just add “don't” in front.
Affirmative Singular: Knock it off, kid!
Affirmative Plural: Knock it off, you guys!
Negative Singular: Don't take candy from strangers, Bobby.
Negative Plural: Don't take candy from strangers, boys.
Latin makes the imperative mood by a process similar to the English one, though it isn't quite as easy. In Latin, you also begin by trimming the present infinitive, specifically the final –re. To form the plural, the ending –te is added to the stem. Third conjugation verbs experience a predictable stem vowel change.
Table 18-1 The Imperative Active
Just as English adds “don't” to the imperative to make it negative, Latin adds a word to the infinitive. The word Latin uses to express a negative command is nī lī,or nī lī te, which is actually the imperative of the verb nī lī,nī lle. Since nī lī means “to be unwilling,” negative commands in Latin are rather quaint. Nī lī mē occidere! (“Don't kill me!”) actually orders the would-be murderer not to want to do the deed. (Be unwilling to kill me!)
The verbs dī -cō , dū cō , faciō, and ferō have slightly irregular imperatives. Due to the fact that these verbs were so common in everyday use, they were clipped down to one-syllable words, namely: dī -c, dū c, fac, and fer. Their plurals are fairly predictable (dī -cite, dū cite, facite, and ferte), and the negative command follows normal rules (nō lī -dī -cere, “don't tell,” etc., …).
In addition to active voice forms for the imperative mood, there are also passive voice forms. While any verb that can take passive voice forms can appear in the imperative passive, usually only deponent verbs are found in Latin literature.
Table 18-2 The Imperative Passive
The imperative passive forms, in the singular, employ the alternate personal ending for the second person singular passive. That is to say, it uses –re instead of –ris. The result is a singular imperative passive that is identical to the present infinitive active. In the case of deponents, of course, the form resembles what the present infinitive active would have looked like had they had any active infinitives.
In the plural, imperative passive forms are the same as the second person plural, present indicative passive. There you will find the regular personal ending –minī.