Truism

n.

1.

An undoubted or self-evident truth; a statement which is pliantly true; a proposition needing no proof or argument; - opposed to falsism. Trifling truisms clothed in great, swelling words. - J. P. Smith.

Noun

1.

truism - an obvious truth

a priori truth, abstraction, aphorism, apothegm, axiom, banality, brocard, bromide, cliche, commonplace, dictate, dictum, formula, general idea, generalization, generalized proposition, glittering generality, gnome, golden rule, gospel, hackneyed expression, law, lieu commun, locus communis, maxim, moral, platitude, postulate, principium, principle, proposition, prosaicism, prosaism, rubber stamp, rule, self-evident truth, settled principle, shibboleth, sweeping statement, tag, theorem, tired cliche, truth, universal truth, verity