needless repetition of an idea, esp. in words other than those of the immediate context, without imparting additional force or clearness, as in “widow woman.”
2.
an instance of such repetition.
3.
Logic.
a.
a compound propositional form all of whose instances are true, as “A or not A.”
b.
an instance of such a form, as “This candidate will win or will not win.”
Needless repetition of the same sense in different words; redundancy.
An instance of such repetition.
Logic An empty or vacuous statement composed of simpler statements in a fashion that makes it logically true whether the simpler statements are factually true or false; for example, the statement Either it will rain tomorrow or it will not rain tomorrow.
[Late Latin tautologia, from Greek tautologiā, from tautologos, redundant : tauto-, tauto- + logos, saying; see -logy.] tau'to·log'i·cal (tôt'l-ŏj'ĭ-kəl), tau'to·log'ic (-ĭk) adj., tau'to·log'i·cal·ly adv.
1579, from L.L. tautologia "representation of the same thing" (c.350), from Gk. tautologia, from tautologos "repeating what has been said," from tauto "the same" + -logos "saying," related to legein "to say" (see lecture).