The doctrines and opinions of the Pyrrhonists or sceptical philosophers; universal doubt; the scheme of philosophy which denies the certainty of any knowledge respecting the phenomena of nature.

In theology, a doubting of the truth of revelation, or a denial of the divine origin of the christian religion, or of the being, perfections or truth of God. Irreligious scepticism or atheistic profaneness. Let no despondency or timidity or secret scepticism lead any one to doubt whether this blessed prospect will be realized.