1.
someone, somebody
An unspecified person.
Forms
誰 (who) + か (question particle) = someone
Indefinite pronoun pattern
Question word + か = indefinite:
NEGATIVE FORMS (with も + negative verb):
か VS も: か makes the question word indefinite and positive (someone, something); も with a negative verb makes it universally negative (no one, nothing). The pair is the standard way Japanese expresses English 'some-' and 'no-' words.
Common patterns
In questions, 誰か is often best translated 'anyone' rather than 'someone': 誰かいませんか is 'Is anyone there?'
Related Words
Related:
何か (something)
Related:
どこか (somewhere)
Related:
いつか (sometime)
Compare:
誰も (nobody)
Compare:
どなたか (someone)
Related:
どれか (one of them)