This is the 594th most frequent Estonian word.
võimatu
"Võimatu" means "impossible" in English.
Here, 'võimatu' is used as an adjective to describe a situation or state that cannot be believed.
Seda on võimatu uskuda.
It is impossible to believe this.
Here, 'võimatu' describes a difficulty in comprehending someone's behavior, serving as the subject of the sentence.
Võimatu on mõista, miks ta nii käitub.
It is impossible to understand why he acts this way.
In this sentence, 'võimatu' functions as an adjective describing an activity or task that cannot be done.