Teijo

Originally probably Teiko (compare Reijo < Reko), from vernacular forms of Tyko, Tycho, Latinised form of Danish Thyge, either from Latin Tychō, Tychicus, Ancient Greek Τύχων (Túkhōn), Τυχικός (Tukhikós), or from short form of names beginning with Old Norse Þur, a variant of the thunder god's name Thor.