Principal Parts


Verbs can appear in many ways. There are verbal nouns (gerunds), verbal adjectives (participles), and, of course, verbs behaving as verbs. All the information you need to create any of the forms that a verb can possibly take is contained in its principal parts. English verbs also have principal parts, such as drink, drank, drunk or lie, lay, lain or go, went, gone. The first part is the simple present, the second is the simple past, and the third is the past participle. Most Latin verbs have four principle parts. Let's use the verb capio, capere, cepi, captum, as our example.



The FIRST principal part, capio I take is the first person singular, present indicative active.  It is the form traditionally used to refer to a verb and how you look it up in a dictionary.  It also tells you whether or not it is an -io verb, which capio clearly is.


The SECOND principal part, cap ere to take is the present infinitive active.  Latin verbs are divided into four groups called conjugations based on the ending of this form. It is important to know to which conjugation a verb belongs because it determines how its present, imperfect, and future tense forms are made.


first conjugation


second conjugation


third conjugation


fourth conjugation


These first two principal parts also provide the information you need to form the imperative, the present active participle, the future passive participle (gerundive), and the gerund.  The last two principal parts are for all the other possible forms.


The THIRD principal part, cepi I took is the first person singular, perfect indicative active.  It provides the stem needed for the perfect, pluperfect, and future perfect tenses, and the perfect infinitive, active voice only.


The FOURTH principal part, captum take is the supine.  From its base the perfect passive and future active participles are made. The perfect passive participle is especially important since it is used with the verb sum to create all the passive voice forms in the perfect system.


There are two traditions for listing the fourth principal part of Latin verbs. One is to supply the supine as this book does. The other tradition is to provide the perfect passive participle, and if no perfect passive participle exists for a verb, the future active participle is used instead. e.g. sum, esse, fui, futurus to be. It is important to note that some verbs, such as timeo, timere, timui to fear, have no fourth principal at all.

Most Latin verb forms can be described in terms of person, number, tense, mood, and voice.  Here is a breakdown of each of these terms.


PERSON refers to the speaker's point of reference. The FIRST person is the speaker: ego I.  The SECOND person is the person being spoken to: tu you.  The THIRD person is anyone or anything else.


NUMBER refers to quantity, singular or plural.  The plural of ego I is nos we, of tu you it's vos you. Since

the endings for these persons are distinct, the nominative case forms of these pronouns aren't necessary.  They are only used to express emphasis. For the third person however, the subject isn't clear unless the reference is obvious, so watch for a noun or pronoun in the nominative.  Ordinarily the subject of a third person verb will remain the same until another nominative appears.


VOICE refers to the relationship of the subject to the verb.

ACTIVE voice shows the subject performing the action.


          Ianuam aperiebam.        I was opening the door.


PASSIVE voice shows the subject receiving the action.


          Ianua aperiebatur.                   The door was being opened.


MIDDLE voice suggests that the subject is performing the action either to
itself, for its own benefit, or has a deep personal interest in an action.


          Ianua aperiebatur.         The door was opening.


In the present system tenses (i.e., the present, imperfect, and future), Latin uses special sets of personal endings, one to signify active voice, and another to show passive and middle voice.
























As you can see, the forms for middle voice are identical to those for passive voice, which can pose a point of confusion since middle voice reads with an active sense.  Occasionally you will find a regular verb used in middle voice, but for the most part Latin has restricted a certain group of verbs called deponents to middle voice in form and meaning, which is why deponents look like they only have passive forms but always have active meanings.  


In the perfect system tenses (i.e., the perfect, pluperfect, and future perfect), Latin splits ways to express them.  For active voice there are special personal endings.  They are attached to the third principal part of a verb minus the final -i.  
























For passive (and middle) voice in the perfect system, you need the perfect passive participle with a form of the verb sum in the present, imperfect, or future tense for the perfect, pluperfect, or future perfect tenses respectively. Since participles are verbal adjectives, and adjectives must agree in gender, case, and number, the form the participle itself takes can vary. The following are examples using the verb ago in masculine gender.





actus sum

acti sumus

actus eram

acti eramus

actus ero

acti erimus

actus es

acti estis

actus eras

acti eratis

actus eris

acti eritis

actus est

acti sunt

actus eras

acti erant

actus erit

acti erunt


TENSE refers to more than simply the time of an action. There is also an element called aspect involved. Aspect is the way the speaker views an action, either as in progress or completed.  For example, I was watching the show says the action was in progress at some time in the past, as opposed to I (have) watched the show, which declares it a finished act. Latin has six tenses, one for each time frame (i.e. now, earlier, and later) in each of the two aspects as this table illustrates.













future perfect