c. 1400, "actually, in fact, in a real manner," originally in reference to the presence of Christ in the Eucharist, "substantially," from real (adj.) + -ly (2). The general sense is from early 15c. Purely emphatic use dates from c. 1600, "indeed," sometimes as a corroboration, sometimes as an expression of surprise or a term of protest; interrogative use (as in oh, really?) is recorded from 1815.