Sup`po*si"tion (?), n. [F. supposition, L. suppositio a placing under, a substitution, fr. supponere, suppositium, to put under, to substitute. The word has the meaning corresponding to suppose. See Sub-, and Position.]
The act of supposing, laying down, imagining, or considering as true or existing, what is known not to be true, or what is not proved.
That which is supposed; hypothesis; conjecture; surmise; opinion or belief without sufficient evidence.
This is only an infallibility upon supposition that if a thing be true, it is imposible to be false.
He means are in supposition.
© Webster 1913.