Where does “чайок” come from?

чайок (Ukrainian) comes from Proto-Slavic čajьka, from Proto-Slavic -ьka, from Proto-Balto-Slavic -ikaʔ, from Proto-Indo-European -ikeh₂.

Ancestry of “чайок”, step by step

чайок traces back through two separate lines of ancestry.

via Proto-Slavic čajьka

StepLanguageWordMeaning
1Proto-Slavicčajьkagull
2Proto-Slavic-ьka—
3Proto-Balto-Slavic-ikaʔ—
4Proto-Indo-European-ikeh₂—

via Ukrainian чай

StepLanguageWordMeaning
1Ukrainianчайtea
Every word from Proto-Indo-European -ikeh₂ →Every word from Proto-Slavic -ьka →Every word from Proto-Slavic čajьka →