کسی

What it means

کسی (kasi) is an indefinite pronoun built from کس (kas, person) plus the indefinite suffix ی (-i). In affirmative sentences and questions it means “someone” or “anyone”: کسی اومد؟ (kasi umad?, did someone come? / did anyone come?). In negative sentences it means “nobody” or “no one”: کسی نیومد (kasi nayumad, nobody came). This positive/negative flip is a core feature of Persian indefinite pronouns, shared with چیزی (chizi, something/nothing), جایی (jâyi, somewhere/nowhere), and هیچ‌کس (hichkas, nobody, a reinforced form). The reinforced negative هیچ‌کسی (hichkasi) is more emphatic: absolutely nobody.

How to use it

• کسی خونه‌ست؟ (kasi khunas?) “Is anyone home?”
• کسی نبود (kasi nabud) “There was nobody there.”
• کسی می‌دونه؟ (kasi midune?) “Does anyone know?”
• دنبال کسی می‌گردم (donbâl-e kasi migardam) “I’m looking for someone.”

Cultural note

The polarity-sensitive behavior of کسی is a pattern Iranians use without a second thought, but it is genuinely tricky for learners because English splits the work across separate words (someone vs. anyone vs. nobody). Once you internalize that کسی in a negative clause means nobody, a large class of conversational structures opens up. Note also the honorific use: گفتم کسی اومد (goftam kasi umad) in storytelling can sometimes sound slightly diminutive, referring to a person without naming them, while آدمی (âdami) or یکی (yeki, someone, one person) can substitute with slightly different nuances of familiarity.

References

• Dehkhoda
• Vajehyab