This is the 542nd most frequent Finnish word.
tiedä
"Know" (imperative or negative present form of "tietää").
The word 'tiedä' is the imperative or indicative active present form of 'tietää,' meaning 'to not know' in this negation.
En tiedä, mitä tehdä.
I don't know what to do.
Here, 'tiedä' indicates questioning someone's knowledge or awareness.
Kuka sen tiedä?
Who knows that?
The word 'tiedä' functions as an imperative command instructing the listener to acknowledge something.