Capitulum Decimum - Grammatica

THIRD DECLENSION NOUNS - masculine and feminine - Some nouns of the third declension change spelling from the nominative to the genitive form.  Be sure to learn both the nominative and genitive.  Remember that the spelling to form all cases except the nominative is based on the genitive form.  All other endings are added to the stem found by dropping the -is from the genitive form, e.g., leō, leōnis; pēs, pedis; dens, dentis; homō, hominis

THIRD DECLENSION NOUNS - neuter - In the third declension the gender of each noun must be memorized.  The nominative form does not provide a clue to gender. We see a few in this chapter: flumen, fluminis; mare, maris; animal, animālis.  They are presented more fully in Chapter 11.

AGREEMENT OF FIRST AND SECOND DECLENSION ADJECTIVES - Adjectives of the first and second declension (-us, -a, -um) keep their first and second declension endings although they may modify a third declension noun.  Adjectives must agree with nouns in case, number and gender, but need not be in the same declension, e.g. magna vōx, magnae vōcis; multae avēs, multārum avium; magnus leō, magnī leōnis; multī hominēs, multōrum hominum; parvum flumen, parvī fluminis; ferum animal, ferī animālis.

IRREGULAR FORMS - second declension noun deus






deī (diī, dī)






deōrum (deum)



deīs (diīs, dīs)



deīs (diīs, dīs)


-IŌ VERBS OF THE THIRD CONJUGATION - Some verbs of the third conjugation have -iunt in the third person plural and -iō in the first person singular, e.g., facere (to do, to make), parere (to give birth, to bring forth), accipere (to receive, to accept), aspicere (to look at)

INFINITIVES - The infinitive is a form of the verb used as a noun.  It is not declined.  An infinitive is neuter in genter.  It may be active or passive.  The active infinitive has the ending -re.  The passive infinitive has the ending -rī in the first, second and fourth conjugations.  Third conjugation passive infinitives end in .  A paradigm in chart form:





vocāre = to call

vocārī = to be called


tenēre = to hold

tenērī = to be held


pōnere = to put

pōnī = to be put


audīre = to hear

audīrī = to be heard



            The infinitive can be used as the subject of a sentence.  It is neuter in gender.  Examples:

Errāre est humānum.

To err is human.

Vidēre est crēdere.

Seeing is believing.


            The infinitive is frequently used as a complementary infinitive.  Some Latin verbs require another verb form in order to complete there meaning, e.g., posse and timēre.  Examples:

Canis volāre nōn potest.

A dog cannot fly.

Hominēs ambulāre possunt.

Men can walk.

Neptūnus natāre potest.

Neptune can swim.

Mercūrius volāre potest.

Mercury can fly.

Puer ascendere timet.

The boy is afraid to climb.


            The infinitive is used after verbs of saying, knowing, thinking and perceiving (so-called "verbs of the head") to communicate an indirect statement. The subject of the infinitive is in the accusative case.  In English such indirect statement clauses are usually introduced by "that".  Examples:  

Direct Statement - Quotes

Indirect Statement - . . .that. . .

Puerī: "Puella canit."

Puerī puellam canere dīcunt.

Mārcus: "Quīntus ad terram cadit."

Mārcus Quīntum ad terram cadere dīcit.

Mārcus: "Quīntus...est...mortuus."

Mārcus Quīntum mortuum esse dīcit.


Note that when a linking verb (esse) is used in the indirect statement, the predicate nominative or adjective used with the linking verb must be in the accusative case.  The object, if there is one, is also, of course in the accusative case: Aemilia dīcit Mārcum Iūliam pulsāre.

ENIM - this means the same as nam, but it can never be the first word in its sentence or clause, unlike nam. Compare these examples:

Neptūnus natāre potest.  Is enim deus maris est.

Mercūrius autem volāre potest, nam in pedibus eius alae sunt.