Y*wis" (?), adv. [OE. ywis, iwis, AS. gewis certain; akin to D. gewis, G. gewiss, and E. wit to know. See Wit to know, and Y-.]
Certainly; most likely; truly; probably.
[Obs. or Archaic]
"Ywis," quod he, "it is full dear, I say."
She answered me, "I-wisse, all their sport in the park is but a shadow to that pleasure that I find in Plato."
A right good knight, and true of word ywis.
⇒ The common form iwis was often written with the prefix apart from the rest of the word and capitalized, as, I wis, I wisse, etc. The prefix was mistaken for the pronoun, I and wis, wisse, for a form of the verb wit to know. See Wis, and cf. Wit, to know.
Our ship, I wis,
Shall be of another form than this.
© Webster 1913.