Look up this word
certainty
In a sentence
Nemyslím si, že bude pršať, ale pre istotu si zoberiem dáždnik.
I don't think it will rain, but I'll take an umbrella just in case.
S istotou odpovedala na všetky otázky.
She answered all the questions with assurance.
Nevieme s istotou, či Tom príde.
We don't know for sure if Tom will come.
S istotou viem, že kľúče sú v taške.
I know for certain the keys are in the bag.
Examples from Tatoeba (CC BY 2.0 FR).
Source
Slovak National Corpus (SNK) ↗English gloss from the frequency publish path. Includes Tatoeba example sentences when present.
Full attribution on References.