If you replace (in cyrillic script) viki[-pedia] to encyclo[-pedia] (because you can't do a whole word replace, since in inflectional languages like Russian every word has many forms with different endings, so you must replace the beginnings of these words to catch all the inflected wordforms) then vikings become encyclongs.

Vikings == wikings (in Russian spelling)

> echo "wikings" | sed "s;wiki;encyclo;"

# which is what enci.ru did

"encyclongs"