'virallisesti' originates from Finnish, specifically the adjective 'virallinen', where the root 'virka' meant 'office' or 'duty' and the suffix '-linen' formed adjectives; the adverbial suffix '-sti' produced 'virallisesti'.

'virallinen' was formed from the noun 'virka' plus the adjectival suffix '-linen'; later the adverb was formed by adding '-sti' to make 'virallisesti', the modern Finnish adverb meaning 'officially'.

Initially it related to 'pertaining to an office or official duty', and over time the adjective 'virallinen' and the adverb 'virallisesti' came to mean 'formal, official' and 'officially' in general usage.