This is the 150th most frequent Estonian word.
ei
"Ei" means "no" in English.
In this question, 'ei' serves as a negation to the verb 'teadsid', forming a negative question indicating surprise or inquiry about ignorance.
Kas sa ei teadnud seda?
Did you not know that?
In this sentence, 'ei' is used as a negation particle, modifying the verb 'lähe' to indicate that the action will not take place.
Ma ei lähe täna poodi.
I am not going to the store today.
Here, 'ei' is used first as an interjection meaning 'no' and then as a negation particle modifying the verb 'ei ole' to negate the state of being hungry.