Third Declension + Third Declension I-Stem

THIRD DECLENSION + THIRD DECLENSION I-STEM

Third Declension

As you know, Latin groups its nouns into five families called “declensions” and nouns in the same declension will follow the same paradigm (pattern of endings).
The third declension paradigm will NOT look exactly like the first or second declensions, however.
Just as you did not put 1st declension endings on a 2nd declension noun (or vice versa), you will not put either 1st or 2nd declension endings on a 3rd declension noun (or vice versa).
The masculine and feminine third declension paradigm of endings (also printed on p. 78 of your textbook) is as follows:

singularplural

Nominative:[various]-ēs

Genitive:-is-um

Dative:-ī-ibus

Accusative:-em-ēs

Ablative:-e-ibus

The neuter third declension paradigm of endings (also printed on p. 82 of your textbook) is as follows:

singularplural

Nominative:[various]-a

Genitive:-is-um

Dative:-ī-ibus

Accusative:[various]-a

Ablative:-e-ibus

Neuter rule: for neuternouns, the nominative and accusative endings are the same. This is true across the entire language.
Now look at this sample third declension noun pax, pacis, f. peace. The endings will appear in boldfaced blue.

singularplural

Nominative:paxpacēs

Genitive:pacīspacum

Dative:pacīpacibus

Accusative:pacempacēs

Ablative:pacepacibus

The case constructions are the same for every declension. I.e. It does NOT matter what declension a noun belongs to as to how it is being used in a sentence. What maters is the case of the noun.
Nominative case is going to be the subject or predicate no matter what declension the noun is in.
pax Rōmāna bona longaque fuerat.
mīlesmultōs gladiōs ad castra portābat.
mea soror nōn mē amat.
Accusative case is going to be the direct object or place to which (or some other accusative construction) no matter what declension it is in.
Augustus pacem Rōmānam instituit.
īnimicus mīlitem gladiō mox oppugnābit.
parentēs magistrīque semper meam sorōremnōn mē laudant.
The same is true for any of the constructions, for any case.

Declining Nouns

To decline ANY Latin noun (or adjective), you need to follow a few simple steps.
STEP #1: Start with the noun in its genitive singular form
N.B. All Latin dictionaries list the nominative singular form and the genitive singular ending
If a dictionary includes a dot ( · ), it does that to show you where you can remove the nominative ending and add the genitive ending listed to decline the noun
SAMPLE ENTRIES: host·is, -is, m.f. enemy; philēm·a, -atis, n. kiss
hostis and philēma are the nominative singular form
N.B. only the –isof the –atis listed in philēmatis is the actual genitive singular ending.
the ( · ) shows you how to form the genitive formwith the information listed
here, the genitive forms are hostis and philēmatis
TIP: For 3rd declension, you MUST memorize both the nominative and genitive forms of each noun so you are able to produce the base of the noun. You have to memorize the genitive form in order to be able to put the endings on the proper base.
STEP #2: Remove the noun’s genitive ending
TIP: you may want to think of declining like a simple math problem.
EXAMPLE: (hostis) –– (-is) = host-
EXAMPLE: (philēmatis) –– (-is) = philēmat-
STEP #3: Add an ending to the base of the noun.
Now that you have the base of the noun, you can change the noun to whatever case and number you want.
Nagging question: “So there really isn’t just one nominative ending? Seriously?!?”
Yes…and no. There are, of course, some patterns, but there are too many to categorize them all. A sample below shows you how this is true:
-[consonant]s, -[consonant]tis:
gēns, gentis
mēns, mentis
mons, montis
pons, pontis,
mors, mortis
-tās, -tātis:
auctoritās, auctoritātis
cīvitās, cīvitātis
dignitās, dignitātis
gravitās, gravitātis
potestās, potestātis
-or, -oris:
arbor, arbōris
gladiātor, gladiātōris
honor, honōris
imperātor, imperātōris
soror, sorōris
-(vowel)x, -(vowel)cis
arx, arcis
dux, ducis
lux lucis,
nex, necis
pax, pacis
prex, precis
-(vowel)x, -(vowel)cis
grex, gregis
lex, legis
rēx, regis
-men, -minis, n.
agmen, agminis, n.
carmen, carminis, n.
flūmen, flūminis, n.
gramen, graminis, n.
lūmen, lūminis, n.
Scan the table below to see how first, second, and third declension fit into the overall scheme of noun declension.

Declension / Nom. sing. / Gen. sing. / Gen. ending / Base
1st (MF) / fēmina / fēminae / -ae / fēmin-
2nd (MF) / amīcus
gener / amīcī
generī / -ī / amīc-
gener-
2nd (Neuter) / rēgnum / rēgnī / -ī / regn-
3rd (M & F) / mīles / mīlitis / -is / mīlit-
3rd (Neuter) / caput / capitis / -is / capit-
4th (MF) / exitus / exitūs / -ūs / exit-
4th (Neuter) / genu / genūs / -ūs / gen-
5th (MF) / faciēs / faciēī / -ēī / faci-

Third Declension I-Stem

Some nouns in the third declension have slightly different endings, incorporating additional “-i”s. Such nouns are called “i-stem” nouns.

How can you identify a noun as being in this category? The textbook lists three rules on p. 87, which I have rephrased as follows:

Rule One: Nouns that end in–isin the nominative singular, and have the same genitive singular form as its nominative are i-stem.
Examples
hostis, hostis, m. enemy
ignis, ignis, m. fire
fēlis, fēlis, m.f. cat
fīnis, fīnis, m. end, boundary
nāvis, nāvis, f. ship
exceptions: canis (dog), iuvenis (young man)
These nouns are almost invariably masculine or feminine.
A noun ending in –es that otherwise has the same genitive singular as its nominative would fall under this rule too.
aedēs, aedis, f. house
fēlēs, fēlis, m.f. cat
caedēs, caedis, f. murder, slaughter
exceptions: sedēs (seat) and vatēs (prophet)

Rule Two: Nouns that are one syllable in the nominative singular and have a base ending in two consonantsare i-stem.
Examples:
nox, noctis, f. night
urbs, urbis, f. city
These nouns are almost invariably masculine or feminine.

Rule Three: Nouns that end in –nsor –rs in the nominative singular are i-stem.
Examples:
gēns, gentis, f. race, tribe, family
mens, mentis, f. mind
mors, mortis, f. death
pars, partis, f. direction, part
pōns, pontis, m. bridge
infans, infantis, m.f. baby
These nouns are almost invariably masculine or feminine.
N.B. In most cases, these nouns will also qualify as i-stem based on Rule Two above.

Rule Four: Neuter nouns that look like animalor mare are i-stem. I.e., Neuter nouns that end in –alor –e are i-stem.
Examples
animal, animālis, n. animal
capital, capitālis, n. crime punishable by death
tribūnal, tribunālis, n. raised platform
vectigal, vectīgālis, n. tax
mare, maris, n. sea
sedīle, sedīlis, n. seat
Neuter nouns ending in –ar also fall into this category, but they are rare.
calcar, calcāris, n. spur
exemplar, exemplāris, n. - example
pulvīnar, pulvīnāris, n. – cushioned couch

I-Stem Declension Paradigms

The masculine and feminine third declension i-stem paradigm of endings (also printed on p. 88 of your textbook) is as follows:

singularplural

Nominative:[various]-ēs

Genitive:-is-ium

Dative:-ī-ibus

Accusative:-em-ēs

Ablative:-e-ibus

The neuter third declension i-stem paradigm of endings (also printed on p. 88 of your textbook) is as follows:

singularplural

Nominative:[various]-ia

Genitive:-is-ium

Dative:-ī-ibus

Accusative:[various]-ia

Ablative:-ī-ibus

Now look at this sample third declension i-stem noun cīvis, cīvis, m.f. citizen. The endings will appear in boldface with the i-stem portion in green.

Nominative:cīv[is]civēs

Genitive:cīviscīvium

Dative:cīvīcīvibus

Accusative:cīvemcīvēs

Ablative:cīvecīvibus

Now look at this sample third declension i-stem noun cervīcal, cervīcālis, n. pillow, cushion. The endings will appear in boldface with the i-stem portion in green.

Nominative:cervīc[al]cervīcālia

Genitive:cervīcāliscervīcālium

Dative:cervīcālīcervīcālibus

Accusative:cervīc[al]cervīcālia

Ablative:cervīcālīcervīcālibus