noun

an opinion or conclusion formed on the basis of incomplete information.

conjectures about the newcomer were many and varied

guess,speculation,surmise,fancy,notion,belief,suspicion,presumption,assumption,theory,hypothesis,postulation,supposition,inference,extrapolation,projection,approximation,estimate,rough calculation,rough idea,guesswork,guessing,surmising,imagining,theorizing,guesstimate,shot in the dark,ballpark figure

verb

form an opinion or supposition about (something) on the basis of incomplete information.

many conjectured that the jury could not agree

guess,speculate,surmise,infer,fancy,imagine,believe,think,suspect,presume,assume,hypothesize,take as a hypothesis,theorize,form/formulate a theory,suppose