Ywis

Part of speech: adverb (adv.)

Certainly; most likely; truly; probably. [Obs. or Archaic] "Ywis," quod he, "it is full dear, I say." Chaucer. She answered me, "I-wisse, all their sport in the park is but a shadow to that pleasure that I find in Plato." Ascham. A right good knight, and true of word ywis. Spenser.