Where does “найздоровіший” come from?

найздоровіший (Ukrainian) comes from Russian наи-, from Proto-Slavic *najь- — used to form the superlative of adjectives and adverbs, taking the form of comparative as the basis; similar to most and -est.

Ancestry of “найздоровіший”, step by step

StepLanguageWordMeaning
1Russianнаи-Prefix forming superlatives from comparative...
2Proto-Slavic*najь-used to form the superlative of adjectives and adverbs, taking the form of comparative as the basis; similar to most and -est
Every word from Proto-Slavic *najь- →Every word from Russian наи- →