Conjecture

Part of speech: noun (n.)

An opinion, or judgment, formed on defective or presumptive evidence; probable inference; surmise; guess; suspicion. He [Herodotus] would thus have corrected his first loose conjecture by a real study of nature. Whewell. Conjectures, fancies, built on nothing firm. Milton.

Part of speech: verb (v.)

To arrive at by conjecture; to infer on slight evidence; to surmise; to guess; to form, at random, opinions concerning. Human reason can then, at the best, but conjecture what will be. South.

Part of speech: verb (v.)

To make conjectures; to surmise; to guess; to infer; to form an opinion; to imagine.