Tautological (adjective)

Describing a statement or proposition that is true by definition, or a statement that is true by virtue of its logical structure.

Origin:

Derived from the greek words "tauto" (meaning "same") and "logos" (meaning "word" or "accoun.t")

Examples:

1. The statement "all bachelors are unmarried men" is tautological.
2. A circle is a round shape, is a tautological statement.
3. The phrase "necessary necessity" is tautological.
4. The argument that the earth is flat is tautological.
5. The definition of a square as a rectangle with four equal sides is tautological.