Third declension: overview

You learned the endings of τίς, τί in 9.1. This is basically the same set of endings that you will find now in the third declension (even though the interrogative pronoun / adjective is not considered to belong to the third declension).

	singular	plural
nominative	-ς *	-ες
genitive	-ος	-ων
dative	-ι	-σι(ν)
accusative	-α *	-ας

*In the cases marked with an asterisk, some nouns of the third declension are different: in the Nominative, they may have no ending, and in the accusative, they may take ν instead of α.

While the stems of the 1st declension typically end in the vowel α / η, and those of the 2nd declension in o, stems of the 3rd declension may end a) in a variety of consonants or b) in the vowels ι or υ. To avoid confusion when learning the 3rd declension it is important to divide it, in the first place, into these two groups. The stems ending in consonants will prove to be different enough to warrant a further division into subtypes corresponding to their phonetic differences. You may want to review the classification of consonants in 2.2. Here is an overview of the consonantal stems you will encounter in the third declension. We will spread their study and practice over several lessons. If you are curious about the contrast between the stem in the Nominative and the general stem, check the footnotes.

Types of consonants	"General" stems shown in the Genitive	Nominative	mark of the Nom	Citation
Liquids: λ ρ	ῥητορ-ος	ῥήτωρ	long vowel	ὁ ῥήτωρ, ῥήτορος
Dental stops : τ δ θ	ἐλπιδ-ος	ἐλπιδ-ς > ἐλπίς¹	+ ς	ἡ ἐλπίς, ἐλπίδος
Dental stops : τ δ θ	πραγματ-ος	πρᾶγμα²	(neuter) no mark	τὸ πρᾶγμα, πράγματος
and the dental nasal ν	αἰων-ος	αἰών	no mark: the vowel is long throughout	ὁ αἰών, αἰῶνος
and the dental nasal ν	δαιμον-ος	δαίμων	long vowel	ὁ δαίμων, δαίμονος
Labial stops : π β φ	κλωπ-ος	κλώψ	+ ς	ὁ κλώψ, κλωπός
Palatal stops : κ γ χ	φαλαγγ-ος	φάλαγξ	+ ς	ἡ φάλαγξ, φάλαγγος
*to be studied later!*
The group ντ	λεοντ-ος	λέων²	long vowel	ὁ λέων, λέοντος
*to be studied* *much later!*
Sibilant : σ	γενεσ-ος > ε-ος > γενους	γένος³	different vowel	τὸ γένος, γένους

ἡ ἅλς, ἁλός ⁴, because λ and ῥ undergo no change when they are followed by σ. One important trait of third declension nouns must be kept in mind: when the stem in the nominative differs from its form in the genitive, it is the latter form of the stem that serves as general stem, i.e. is the basis for all the other cases.

I decline here ὁ ῥήτωρ in combination with the adjective κακός, κακή, κακόν, to illustrate the fact that the noun and the adjective follow each its own declension.

	singular	plural
nominative	ὁ κακὸς ῥήτωρ	οἱ κακοὶ ῥήτορες
genitive	τοῦ κακοῦ ῥήτορος	τῶν κακῶν ῥητόρων
dative	τῷ κακῷ ῥήτορι	τοῖς κακοῖς ῥήτορσι(ν)
accusative	τὸν κακὸν ῥήτορα	τοὺς κακοὺς ῥήτορας

There is a small group of nouns whose stem ends in ῥ that will require some attention later, not because of consonantal changes but because their internal vowel changes. They are the names of kin (πατήρ = father, μήτηρ = mother, θυγάτηρ = daughter, and ἀνήρ = man). For future reference, cllick here for their declension.

3) The general stem γενεσ- contrasts with the Nominative γένος. This is called "gradation of the vowel." This group of 3rd declension words will be studied later!

4) In Classical Greek ὁ ἅλς, ἁλός = salt; ἡ ἅλς, ἁλός = the sea. Koinê Greek has the neuter τὸ ἅλα, ἅλατος.