誰か

1. Origins, structure, and basic meaning

• Structure: 誰か (だれか) adds the indefinite particle か to 誰 and means someone whose identity is unspecified.
• Basic usage: Its role changes with the following particle, as in subject 誰かが and recipient 誰かに.

2. Common pitfalls and similar expressions

• An unspecified person
  • Unlike a bare question word, it can refer within a statement to someone who exists but is not specified.