Indefinite pronouns (belgisizlik zamirleri) refer to non-specific people, things, or amounts.

Common Indefinite Pronouns:

• Biri / Birisi: Someone, somebody (Biri geldi - Someone came)
• Herkes: Everyone, everybody (Herkes burada mı? - Is everyone here?)
• Kimse: Anyone, anybody (in questions/negatives); No one, nobody (with negative verb)
  • (Kimse var mı? - Is anyone there?)
  • (Kimse gelmedi. - Nobody came.)
• Hiç kimse: No one, nobody (stronger, used with positive or negative verb for same meaning) (Hiç kimse bilmiyor. - Absolutely no one knows.)
• Bir şey: Something (Bir şey yedim. - I ate something.)
• Hiçbir şey: Nothing (Hiçbir şey anlamadım. - I understood nothing.)
• Bazısı / Bazıları: Some (of them) (Bazıları geç kaldı. - Some of them were late.)
• Hepsi: All (of them) (Hepsi gitti. - All of them went.)
• Birkaçı: A few (of them) (Birkaçı soru sordu. - A few of them asked questions.)
• Başkası: Someone else, another person (Başkası yapsın. - Let someone else do it.)
• Her biri: Each one (Her biri farklıydı. - Each one was different.)
• Falan / Filan: Such and such, and so on, etc. (colloquial) (Kitap, defter falan aldım. - I bought books, notebooks, and so on.)

Declension:

Many indefinite pronouns can decline for case. The pattern of declension usually follows standard noun or pronoun rules, applying vowel harmony and buffer consonants where necessary.

Example with "Biri":

• Nominative: Biri (Someone)
• Genitive: Birinin (Someone's)
• Accusative: Birini (Someone - direct object)
• Dative: Birine (To someone)
• Locative: Birinde (On someone, with someone)
• Ablative: Birinden (From someone)

Example with "Herkes":

• Nominative: Herkes (Everyone)
• Genitive: Herkesin (Everyone's)
• Accusative: Herkesi (Everyone - direct object)
• Dative: Herkese (To everyone)
• Locative: Herkeste (On everyone, with everyone)
• Ablative: Herkesten (From everyone)

Pronouns like "bir şey" (something) decline on the "şey" part: bir şeyin, bir şeyi, bir şeye, bir şeyde, bir şeyden.

"Hiçbiri" (none of them) and "her biri" (each of them) have the possessive suffix -i already, so they decline like: hiçbirinin, hiçbirini, hiçbirine etc.