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invisible

In a sentence
To hlavné je očiam neviditeľné.
What is essential is invisible to the eye.
Neviditeľný atrament sa zjaví pri teple.
Invisible ink appears when heated.
Pre deti je niekedy strach skoro neviditeľný.
For children, fear is sometimes almost invisible.
Neviditeľný atrament sa ukáže až pri teple.
Invisible ink only appears with heat.
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.