A Latin verb dictionary entry gives up to four individual Latin words (or parts of words) and a translation. The four Latin words are called the four principle parts. It looks something like this:
Cantāre—to sing—is a first conjugation verb whose stem doesn’t change over its four principle parts, so the dictionary entry doesn’t waste space by writing it out completely: we just drop the -ō from the first principle part to get cant the common stem. The four principle parts mean the following:
The perfect tense refers to past events, and is the most common tense for doing so. The two tenses in English that it covers are the present perfect (he has done) and the simple past (he did).
To form the perfect tense of a verb, we take the third principle part of our dictionary entry, drop the -ī from the end, and add personal endings:
The perfect tense endings in Latin are unique: all other tenses follow a consistent pattern of endings. The perfect tense endings are as follows:
The imperfect tense also refers to past events, but those which are incomplete in some sense (hence the im-). Examples of translations for the first person singular imperfect cantābam are:
Forming the imperfect tense is slightly more complicated that forming the perfect tense: we need to know the conjugation of the verb before we can begin (see above). The endings showing person and number, however, are consistent across all other tenses.
We begin by looking at the infinitie—the second principle part—of the verb. We then drop the infinitive ending before adding a vowel sound appropriate to each conjugation, as follows:
|Conjugation||Infinitive Ending||Vowel Sound|
For cantāre, we drop the –āre and add -ā- to get cantā (note that just dropping the -re only works for first and second conjugation verbs).
This done, we add the imperfect tense indicator -ba-, and add the following verb endings:
(We were slightly economical with the truth; for some tenses the first person singluar ending is -ō. All others stay the same, promise.)
Therefore to find the second person plural imperfect of cantāre, we take our imperfect ‘stem’ cantā, add to it the imperfect marker -ba-, and append to that -tis to get… cantābatis.