-ος

See also: -ός, ὅσ', and ὅς

Ancient Greek

Etymology 1

From Proto-Hellenic *-os, from Proto-Indo-European *-os. Cognate with the Latin masculine -us (from Old Latin and Proto-Italic *-os both in names and adjectives).

Suffix

-ος • (-os) m (genitive -ου); second declension

2. Added to verbal roots to form an o-grade action noun.

Usage notes

The accent is recessive.

Derived terms

Ancient Greek terms suffixed with -ος (o-grade)

Etymology 2

From Proto-Indo-European *-os.

Suffix

-ος • (-os) n (genitive -εος or -ους); third declension

1. Added to verbal roots to form a noun of result or an abstract noun of action.
   1. Added to the zero-grade.

      ‎ἔπᾰθον (épathon, “I experienced”, aorist) ‎-ος (-os) → ‎πᾰ́θος (páthos, “experience, emotion”)

   2. Added to the e-grade.

      ‎μείρομαι (meíromai, “to receive as one's portion”) ‎-ος (-os) → ‎μέρος (méros, “part”)

Etymology 3

Suffix

-ος • (-os)

1. Nominative singular of masculine and feminine second-declension nouns

   ἄνθρωπος m or f (ánthrōpos, “person”)

2. Masculine nominative singular of first- and second-declension adjectives

   ἄλλος m (állos, “other”)

3. Masculine and feminine nominative singular of second-declension adjectives

   ἄδικος m or f (ádikos, “unjust”)

4. Genitive singular of consonant-stem or uncontracted third-declension nouns

   ὀνόματος n (onómatos, “of a name”)

5. Genitive singular of consonant-stem or uncontracted third-declension masculine or neuter adjectives

   παντός m or n (pantós, “of the whole of”)

Declension

Second declension of -ος; -ου (Attic)

Case / #	Singular	Dual	Plural
Nominative	-ος -os	-ω -ō	-οι -oi
Genitive	-ου -ou	-οιν -oin	-ων -ōn
Dative	-ῳ -ōi	-οιν -oin	-οις -ois
Accusative	-ον -on	-ω -ō	-ους -ous
Vocative	-ε -e	-ω -ō	-οι -oi
Notes:	This table gives Attic inflectional endings. For declension in other dialects, see Appendix:Ancient Greek dialectal declension.

See also

• -η (-ē)
• -ς (-s)

Greek

Etymology

From Ancient Greek -ος (-os).

Suffix

-ος • (-os)

1. An ending found in nouns
   1. In nominative singular form of many masculine nouns

      eg: δρόμος (drómos), καλόγερος (kalógeros), etc

   2. In nominative singular form of few feminine nouns

      eg: μήφος (mífos), διάμετρος (diámetros), etc

   3. In nominative, accusative and vocative singular forms of few neuter nouns

      eg: δάσος (dásos), έδαφος (édafos), etc

2. An ending found in majority of adjectives

Derived terms

Masculine nouns — numbers indicate the current frequencies found on Wiktionary

• Αλέκος (used by, 15)
• άνηθος (used by, 27)
• ανθόκηπος (used by, 0)
• άνθρωπος (used by, 251)
• Αύγουστος (used by, 42)
• γέρος (used by, 21)
• δρόμος (used by, 579)
• ζέφυρος (used by, 23)
• καλόγερος (used by, 141)
• μέτοικος (used by, 132)
• νότος (used by, 37)
• Ουρανός (used by, 122)

Feminine nouns

• Κύπρος (used by, 13)
• ψήφος (used by, 18)
• Αίγυπτος (used by, 18)
• διάμετρος (used by, 50)

Neuter nouns

• κύτος (used by, 0)
• δάσος (used by, 67)
• μίσος (used by, 3)
• θέρος (used by, 8)
• άνθος (used by, 3)
• έδαφος (used by, 9)
• έλεος (used by, 1)

Adjectives

• -ος-η-ο (3,121)
• -ος-α-ο (297)
• -ος-α-ο (3)
• -ος-α-ο (1)
• -ος-η/α-ο (5)
• -ος-ια/η-ο (0)
• -ος-ια-ο (2)
• -ος-ος/α-ο (28)
• -ος-ος/η-ο (1)
• -ος-ος-ο (16)
• -ος-ος-ον (5)