As soon as her doctor allowed her to put her foot out-of-doors she hurried up to Green Gables, bursting with curiosity to see Matthew and Marilla’s orphan, concerning whom all sorts of stories and suppositions had gone abroad in Avonlea.
There are no more uses of "supposition" in the book.
Show samples from other sources
It is a foolish supposition.
She paints a vivid picture, but we must remember it is all mere supposition.