Third-Declension Nouns in All Cases

The Russian third declension is the smallest of the three, but you cannot avoid it: it holds some of the most frequent nouns in the language — ночь ("night"), дверь ("door"), жизнь ("life"), вещь ("thing"), любо́вь ("love"), площадь ("square"), кровать ("bed"), and the kinship pair мать ("mother") and дочь ("daughter"). Every member is feminine and every member ends in a soft sign -ь in the nominative singular. That soft sign is doing real work: it tells you both the gender (these are feminine, unlike masculine -ь nouns like слова́рь) and the declension, so the form and the grammar arrive together. Like the first declension, this page is noun-class-centric: we take a few model nouns and run each one through all six cases, singular and plural, so you see a single word's complete life. The class has exactly two signatures and two irregular members, all flagged below.

Knowing the class on sight: feminine -ь, not masculine -ь

A word ending in -ь can be either feminine (third declension: ночь, дверь) or masculine (second declension: слова́рь, день). The ending alone does not tell you which — you must learn the gender with the word, and the soft-sign gender page gives the lexical shortcuts. But once you know a -ь noun is feminine, its whole paradigm is fixed, and it looks nothing like the masculine -ь pattern: a feminine -ь noun keeps its softness throughout, never adds -ов/-ев, and shows the two signatures below.

Model 1 — ночь (the prototype)

Learn this paradigm cold. Nearly every third-declension noun follows it exactly.

This single table contains both signatures of the declension. Signature one: the genitive, dative, and prepositional singular all collapse into one form, -и — но́чи, но́чи, но́чи, three identical words. So the moment you know a noun is a feminine -ь, three of its six singular cases are settled at once: к но́чи ("toward night," dat), до но́чи ("until night," gen), о но́чи ("about the night," prep). Signature two: the instrumental singular is -ью — но́чью — a uniquely third-declension ending found nowhere else in the noun system. It is doubly useful because но́чью also functions as the adverb "at night," exactly as днём means "in the daytime."

Notice too that the nominative and accusative singular are bare (ночь / ночь — no ending), and that the stress shifts to the ending in the plural oblique cases (ноче́й, ноча́м, ноча́ми, ноча́х) while staying on the stem in nom./acc. plural (но́чи). This end-stress in the plural is typical of the class, though not every noun does it.

Model 2 — дверь (the everyday twin)

дверь behaves exactly like ночь, with one wrinkle that recurs across the class: an irregular instrumental plural in -ьми.

The regular instrumental plural would be дверя́ми, and it exists, but the irregular дверьми́ is the more usual form in living speech. A handful of third-declension nouns prefer or require this -ьми ending: ло́шадь → лошадьми́, дочь → дочерьми́, and the high-frequency set phrase люди́ → людьми́, де́ти → детьми́ (these last two are not third-declension nouns, but they take the same archaic instrumental ending, which is why it is worth recognizing). There is no logical shortcut — you simply learn that this short list takes -ьми. Everything else in the дверь paradigm is pure ночь.

Model 3 — любо́вь and вещь (the small wrinkles)

Two more high-frequency nouns add the last regular wrinkles. любо́вь ("love") is fully regular except that it drops its -о- in every form with an ending — a fleeting vowel: любо́вь → любви́ (gen/dat/prep), любо́вью (instr, where there is no real ending, so the vowel stays). The genitive любви́ is the form you meet first ("declaration of love," "for love of…"), so the drop bites early.

Two notes. The -о- drop is a property of the common noun любо́вь only — the woman's name Любо́вь keeps its -о- (gen Любо́ви, not Любви́), so "I'm waiting for Lyubov" is жду Любо́вь, but "for love" is ра́ди любви́. And вещь shows the genitive plural the whole class shares: *-ей (веще́й), with the soft sign of the stem absorbed into the ending. After the hushing consonant щ this -ей is regular, never *-ов.

Model 4 — мать and дочь (the -ер- irregulars)

Now the two genuine irregulars. мать ("mother") and дочь ("daughter") are feminine -ь nouns, but in every case except the nominative and accusative singular they insert -ер- into the stem: мать → ма́тери, дочь → до́чери. So the bare forms мать and дочь appear only in nom./acc. singular; everywhere else you build on the longer stem ма́тер- / до́чер-.

Once you accept the -ер- extension, these nouns are otherwise regular third-declension words: ма́тери is the expected gen/dat/prep -и (just on the longer stem), ма́терью is the expected instrumental -ью, матере́й is the expected genitive plural -ей. Two extra details: мать and дочь are animate, so their accusative plural copies the genitive plural (ви́жу матере́й, ви́жу дочере́й), while the accusative singular stays bare (ви́жу мать, ви́жу дочь). And дочь, like дверь, prefers the irregular instrumental plural дочерьми́. Stress moves to the ending in the plural oblique cases (матере́й, матеря́м) but stays on the stem in the singular and in the nom. plural (ма́тери).

A note on the masculine outlier путь

You may have heard that путь ("way, path") is "the only masculine third-declension noun." It is a special case worth flagging but not memorizing here: путь takes the third-declension endings in the genitive, dative, and prepositional singular (пути́), but the masculine second-declension ending in the instrumental singular (путём, not *пу́тью). It agrees masculine throughout (до́лгий путь). Because it mixes two paradigms, it gets its own treatment on the путь page; do not let it blur your picture of the otherwise cleanly feminine third declension.

Common Mistakes

Key Takeaways

• The third declension = feminine nouns ending in a soft sign -ь (ночь, дверь, вещь, любо́вь, мать, дочь) — small but extremely high-frequency.
• Signature one: the genitive, dative, and prepositional singular all merge into -и (но́чи, две́ри, ве́щи) — three cases, one form.
• Signature two: the instrumental singular is -ью (но́чью, две́рью, любо́вью), an ending found nowhere else; the genitive plural is -ей (ноче́й, двере́й, веще́й).
• A short list takes the irregular instrumental plural -ьми: дверьми́, лошадьми́, дочерьми́ (and the look-alikes людьми́, детьми́).
• мать and дочь insert -ер- in every case but the nom./acc. singular (ма́тери, до́чери, матере́й, дочере́й); любо́вь drops its -о- (любви́); the woman's name Любо́вь keeps it (Любо́ви).
• путь is a masculine mixed-paradigm outlier — handle it separately, not as a third-declension model.