Synonyms for Surmise:

n.

hazard, read between the lines, underestimate, overestimate, put two and two together. belief (noun)
opinion.
conjecture (noun)
attempt, study at guess, opinion.
guess, conclusion (noun)
hypothesis, opinion, speculation, conjecture, supposition, attempt.
surmise (noun)
hypothesis, speculation, suspect, conjecture, supposition, surmisal, guess.

v.

come to a conclusion (verb)
conclude, assume, suppose, suspect, deduce, infer, imagine, consider, think, presume, guess.
expect (verb)
anticipate, forebode, foreknow, presuppose, contemplate, expect, imagine, suspect, await, foresee, dread, apprehend, envisage, envision.

Other synonyms:

hazard, underestimate, opinion. overestimate. Other relevant words:
conjecture, attempt, hypothesis, speculation, opinion, surmisal, supposition, hazard.

Usage examples for surmise

  1. " It is pure surmise Sir Hilary. – The Grell Mystery by Frank Froest
  2. What happened after that I cannot even surmise – The Chase of the Golden Plate by Jacques Futrelle
  3. For I surmise you intend to marry this Mr. Kirkwood, don't you? – The Black Bag by Louis Joseph Vance