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).
o The third declension paradigm will NOT look exactly like the
first or second declensions, however.
o 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:
Nominative:
Genitive:
Dative:
Accusative:
Ablative:
singular
plural
[various]
-is
-ī
-em
-e
-ēs
-um
-ibus
-ēs
-ibus
 The neuter third declension paradigm of endings (also printed on p.
82 of your textbook) is as follows:
Nominative:
Genitive:
Dative:
Accusative:
Ablative:
singular
plural
[various]
-is
-ī
[various]
-e
-a
-um
-ibus
-a
-ibus
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THIRD DECLENSION + THIRD DECLENSION I-STEM
 Neuter rule: for neuter nouns, 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.
Nominative:
Genitive:
Dative:
Accusative:
Ablative:
singular
plural
pax
pacīs
pacī
pacem
pace
pacēs
pacum
pacibus
pacēs
pacibus
 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.
o Nominative case is going to be the subject or predicate no
matter what declension the noun is in.
 pax Rōmāna bona longaque fuerat.
 mīles multōs gladiōs ad castra portābat.
 mea soror nōn mē amat.
o 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 sorōrem nōn mē
laudant.
o The same is true for any of the constructions, for any case.
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THIRD DECLENSION + THIRD DECLENSION I-STEM
Declining Nouns
 To decline ANY Latin noun (or adjective), you need to follow a few
simple steps.
o 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
o hostis and philēma are the nominative singular
form
o N.B. only the –is of the –atis listed in
philēmatis is the actual genitive singular
ending.
o the ( · ) shows you how to form the genitive
form with the information listed
o here, the genitive forms are hostis and
philēmatis
rd
 TIP: For 3 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.
o 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) = philēmato 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.
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THIRD DECLENSION + THIRD DECLENSION I-STEM
 Nagging question: “So there really isn’t just one nominative ending?
Seriously?!?”
o 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
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THIRD DECLENSION + THIRD DECLENSION I-STEM
 rēx, regis
 -men, -minis, n.
 agmen, agminis, n.
 carmen, carminis, n.
 flūmen, flūminis, n.
 gramen, graminis, n.
 lūmen, lūminis, n.
o 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
amīcī
-ī
amīc-
gener
generī
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-
gener-
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THIRD DECLENSION + THIRD DECLENSION I-STEM
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:
1. Rule One: Nouns that end in –is in the nominative singular, and
have the same genitive singular form as its nominative are i-stem.
a. Examples
i. hostis, hostis, m. enemy
ii. ignis, ignis, m. fire
iii. fēlis, fēlis, m.f. cat
iv. fīnis, fīnis, m. end, boundary
v. nāvis, nāvis, f. ship
vi. exceptions: canis (dog), iuvenis (young man)
b. These nouns are almost invariably masculine or feminine.
c. A noun ending in –es that otherwise has the same genitive
singular as its nominative would fall under this rule too.
i. aedēs, aedis, f. house
ii. fēlēs, fēlis, m.f. cat
iii. caedēs, caedis, f. murder, slaughter
iv. exceptions: sedēs (seat) and vatēs (prophet)
2. Rule Two: Nouns that are one syllable in the nominative singular
and have a base ending in two consonants are i-stem.
a. Examples:
i. nox, noctis, f. night
ii. urbs, urbis, f. city
b. These nouns are almost invariably masculine or feminine.
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THIRD DECLENSION + THIRD DECLENSION I-STEM
3. Rule Three: Nouns that end in –ns or –rs in the nominative
singular are i-stem.
a. Examples:
i. gēns, gentis, f. race, tribe, family
ii. mens, mentis, f. mind
iii. mors, mortis, f. death
iv. pars, partis, f. direction, part
v. pōns, pontis, m. bridge
vi. infans, infantis, m.f. baby
b. These nouns are almost invariably masculine or feminine.
c. N.B. In most cases, these nouns will also qualify as i-stem
based on Rule Two above.
4. Rule Four: Neuter nouns that look like animal or mare are i-stem.
I.e., Neuter nouns that end in –al or –e are i-stem.
a. Examples
i. animal, animālis, n. animal
ii. capital, capitālis, n. crime punishable by death
iii. tribūnal, tribunālis, n. raised platform
iv. vectigal, vectīgālis, n. tax
v. mare, maris, n. sea
vi. sedīle, sedīlis, n. seat
b. Neuter nouns ending in –ar also fall into this category, but
they are rare.
i. calcar, calcāris, n. spur
ii. exemplar, exemplāris, n. - example
iii. pulvīnar, pulvīnāris, n. – cushioned couch
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THIRD DECLENSION + THIRD DECLENSION I-STEM
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:
Nominative:
Genitive:
Dative:
Accusative:
Ablative:
singular
plural
[various]
-is
-ī
-em
-e
-ēs
-ium
-ibus
-ēs
-ibus
 The neuter third declension i-stem paradigm of endings (also printed
on p. 88 of your textbook) is as follows:
Nominative:
Genitive:
Dative:
Accusative:
Ablative:
singular
plural
[various]
-is
-ī
[various]
-ī
-ia
-ium
-ibus
-ia
-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:
Genitive:
Dative:
Accusative:
Ablative:
cīv[is]
cīvis
cīvī
cīvem
cīve
civēs
cīvium
cīvibus
cīvēs
cīvibus
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THIRD DECLENSION + THIRD DECLENSION I-STEM
 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:
Genitive:
Dative:
Accusative:
Ablative:
cervīc[al]
cervīcālis
cervīcālī
cervīc[al]
cervīcālī
cervīcālia
cervīcālium
cervīcālibus
cervīcālia
cervīcālibus
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