This is the 20th most frequent Lithuanian word.
kas
"Kas" in Lithuanian means "who" or "what."
In this interrogative sentence, 'kas' acts as a question word meaning 'what', used to ask for the identification of something.
Kas tai yra?
What is this?
In this context, 'kas' is used as a question word meaning 'who', prompting identification of a person.
Kas padėjo tau?
Who helped you?
Here, 'kas' introduces a relative clause and means 'who', referring to a person in declarative context.