Lesson 7: Third Declension

LESSON 7 · Unit II — The Noun System · ~50 minutes + drilling

By the End of This Lesson

Know the basic 3rd-declension endings (memorize one set, use it for both genders)
Find the stem of a 3rd-declension noun from its genitive form
Recognize the four common stem types: mute, liquid, vowel, sigma
Decline σάρξ, αἰών, πατήρ, πνεῦμα, and βασιλεύς
Memorize the 23 vocabulary words for this lesson

Why Third Declension Is Different

For 1st and 2nd declension nouns, the stem stays the same in every form. λόγος, λόγου, λόγῳ — the stem λογ- is visible everywhere.

Third declension is sneakier. The stem often gets distorted in the nominative singular by collisions with the case-ending. So σάρξ ('flesh') doesn't show its real stem in the nominative — you have to look at the genitive σαρκός to see the underlying σαρκ-.

This is why 3rd-declension nouns are listed in dictionaries with two forms: nominative and genitive. The genitive reveals the stem. Lesson 7 vocabulary all uses this format.

The procedure For a 3rd-declension noun, you can find the stem in three steps:

1. Take the genitive singular form. Example: σαρκός.
2. Drop the genitive singular ending -ος. What remains is the stem: σαρκ-.
3. Add the case endings (below) to that stem.

The Endings

3rd declension uses one set of endings for both masculine and feminine, and a slightly different set for neuter. Memorize these — they're more important than any individual paradigm.

3rd Declension Endings

	Masc / Fem		Neuter
	sg	pl	sg	pl
Nom	- / -ς	-ες	- / -	-α
Gen	-ος	-ων	-ος	-ων
Dat	-ι	-σι(ν)	-ι	-σι(ν)
Acc	-α / -ν	-ας	- / -	-α

⚠ Notice The genitive singular is always -ος. This is the key to finding any 3rd-declension stem.

The dative plural -σι(ν) often clashes with the stem, causing spelling changes (the σ in the ending meeting the consonant of the stem). Watch for this in σάρξ paradigm below.

Neuter follows the universal rule: nominative and accusative are identical (singular and plural).

Pattern 1: Mute Stems (κ, γ, χ stems)

When a stem ends in a 'mute' (k-sound: κ, γ, χ; or p-sound: π, β, φ; or t-sound: τ, δ, θ), it collides with the case endings -ς (nom sg) and -σι (dat pl). The combination produces a single letter:

κ + σ → ξ (so σαρκ-ς → σάρξ)
π + σ → ψ
τ + σ → σ

σάρξ, σαρκός, ἡ — 'flesh' (κ-stem)

	Singular	Plural
Nom	σάρξ (σαρκ + ς → ξ)	σάρκες
Gen	σαρκός	σαρκῶν
Dat	σαρκί	σαρξί (σαρκ + σι → ξι)
Acc	σάρκα	σάρκας

Pattern 2: Liquid Stems (ν, ρ stems)

'Liquids' (λ, ρ) and 'nasals' (μ, ν) interact more peacefully with the endings, but they often shed a letter at the nominative singular. αἰών ('age') has stem αἰων-; the nominative drops the σ.

αἰών, αἰῶνος, ὁ — 'age, eternity' (ν-stem)

	Singular	Plural
Nom	αἰών (no ending)	αἰῶνες
Gen	αἰῶνος	αἰώνων
Dat	αἰῶνι	αἰῶσι(ν) (ν drops before σ)
Acc	αἰῶνα	αἰῶνας

πατήρ, πατρός, ὁ — 'father' (ρ-stem, with vowel reduction)

Same pattern as μήτηρ ('mother'); irregular long vs. short stem variations

	Singular	Plural
Nom	πατήρ	πατέρες
Gen	πατρός	πατέρων
Dat	πατρί	πατράσι(ν)
Acc	πατέρα	πατέρας

Why πατήρ is irregular Notice the stem alternates: πατήρ (long ē, no ending) → πατρ- (short, no vowel) → πατέρ- (short, with vowel). This 3-form alternation comes down from PIE roots and survives in μήτηρ ("mother"), θυγάτηρ ("daughter"), and ἀνήρ ("man"). Just memorize the three nominative-genitive-dative-singular forms and the rest follows.

Pattern 3: Neuter -μα Nouns

A huge category — neuter nouns ending in -μα, with stem in -ματ-. Includes πνεῦμα ('spirit'), ὄνομα ('name'), ῥῆμα ('word'), σπέρμα ('seed'), and dozens more.

πνεῦμα, πνεύματος, τό — 'spirit, breath, wind' (-ματ stem)

	Singular	Plural
Nom	πνεῦμα (τ drops at end of word)	πνεύματα
Gen	πνεύματος	πνευμάτων
Dat	πνεύματι	πνεύμασι(ν)
Acc	πνεῦμα (neuter rule)	πνεύματα

Pattern is universal Every -μα noun follows this pattern. Once you know πνεῦμα, you know ὄνομα ("name"), σῶμα ("body"), αἷμα ("blood"), θέλημα ("will"), and the rest. Just substitute the stem.

Pattern 4: -εύς Nouns

Words like βασιλεύς ('king') and ἀρχιερεύς ('high priest') belong to a vowel-stem subgroup of 3rd declension. The stem is βασιλε-, but it interacts oddly with the endings.

βασιλεύς, βασιλέως, ὁ — 'king' (-εύς stem)

	Singular	Plural
Nom	βασιλεύς	βασιλεῖς
Gen	βασιλέως	βασιλέων
Dat	βασιλεῖ	βασιλεῦσι(ν)
Acc	βασιλέα	βασιλεῖς

Sentences

τὸ πνεῦμα τοῦ θεοῦ ἐν ταῖς καρδίαις τῶν ἀνθρώπων.

— to pneuma tou theou en tais kardiais tōn anthrōpōn.

"The Spirit of God [is] in the hearts of men." Three different declensions on display: 3rd-decl neuter (πνεῦμα), 2nd-decl masc (θεοῦ, ἀνθρώπων), 1st-decl fem (καρδίαις).

ὁ Χριστὸς ἀκούει τὰς προσευχὰς τῶν ἁγίων.

— ho Christos akouei tas proseuchas tōn hagiōn.

"Christ hears the prayers of the saints." τῶν ἁγίων is the substantival adjective from Lesson 6 — "of the holy ones."

ὁ πατὴρ τῶν φωτῶν

— ho patēr tōn phōtōn

"the Father of lights" (James 1:17). 3rd-decl ρ-stem + 3rd-decl τ-stem genitive plural.

ἡ χάρις τοῦ κυρίου ἡμῶν Ἰησοῦ Χριστοῦ μετὰ πάντων.

— hē charis tou kyriou hēmōn Iēsou Christou meta pantōn.

"The grace of our Lord Jesus Christ [be] with all" (Pauline benediction). χάρις is 3rd-decl τ-stem (gen χάριτος); πάντων is gen pl of πᾶς ('all').

Translation Exercises

Translate

οἱ ἀρχιερεῖς ἀκούουσι τὴν φωνὴν τοῦ βασιλέως.
τὸ ὄνομα τοῦ πατρός.
ἡ ἐλπὶς τῆς ζωῆς ἐν τῷ Χριστῷ.
τὰ ἔθνη βλέπει τὸ φῶς τοῦ εὐαγγελίου.
ἡ νὺξ ἔρχεται ὅτε οὐδεὶς δύναται ἐργάζεσθαι. [John 9:4 paraphrased; ἔρχεται = "comes," οὐδεὶς = "no one," δύναται = "is able," ἐργάζεσθαι = "to work"]

Answers 1. The high priests hear the voice of the king.
2. The name of the father.
3. The hope of life in Christ.
4. The Gentiles see the light of the gospel. (τὰ ἔθνη = nom pl neuter, taking singular verb per the rule from Lesson 4.)
5. Night comes when no one can work.

Watch — Bill Mounce companion lecture

BBG Ch 10

BBG Ch 10 Third Declension Open on YouTube ↗

Finding the stem from the genitive, mute/liquid/vowel stems, and the universal -μα neuter pattern.

Practice — drill the concepts

Eight drill sets for the trickiest declension — concepts, finding the stem from the genitive, the universal endings, mute stems (σάρξ), liquid stems (αἰών, πατήρ), the -μα family (πνεῦμα and friends), vowel-stems (-εύς, -ις), and full translation. Plenty of repetition to make 3rd decl feel automatic.

Vocabulary — Lesson 7 23 third-declension nouns

Greek (with genitive)	Translit.	Meaning
ὁ αἰών, αἰῶνος	aiōn	age, eternity, world
ὁ ἀνήρ, ἀνδρός	anēr	man, husband
ὁ ἀρχιερεύς, ἀρχιερέως	archiereus	high priest
ὁ βασιλεύς, βασιλέως	basileus	king
ἡ γυνή, γυναικός	gynē	woman, wife
ἡ ἐλπίς, ἐλπίδος	elpis	hope
τὸ ἔθνος, ἔθνους	ethnos	nation; (pl) Gentiles
ὁ ἱερεύς, ἱερέως	hiereus	priest
ἡ μήτηρ, μητρός	mētēr	mother
ἡ νύξ, νυκτός	nyx	night
τὸ ὄνομα, ὀνόματος	onoma	name
ὁ πατήρ, πατρός	patēr	father
ἡ πίστις, πίστεως	pistis	faith, trust
τὸ πνεῦμα, πνεύματος	pneuma	spirit, breath, wind
ἡ πόλις, πόλεως	polis	city
ἡ σάρξ, σαρκός	sarx	flesh, body, human nature
τὸ σῶμα, σώματος	sōma	body
ὁ σωτήρ, σωτῆρος	sōtēr	savior, deliverer
τὸ τέλος, τέλους	telos	end, goal
τὸ ὕδωρ, ὕδατος	hydōr	water
τὸ φῶς, φωτός	phōs	light
ἡ χάρις, χάριτος	charis	grace, favor
ἡ χείρ, χειρός	cheir	hand

Now you've completed the noun system With Lessons 4–7, every Greek noun in the New Testament has a paradigm you can apply. Adjectives (Lesson 6) follow the same patterns. Pronouns (Lesson 8) and prepositions (Lesson 9) are next; then we move to the verb system in Unit III. Drill the 3rd-declension endings until they're automatic — they're the foundation for participles later.