Tautology

A repetition of the same meaning in different words; needless repetition of an idea in different words or phrases; a representation of anything as the cause, condition, or consequence of itself, as in the following lines: --//The dawn is overcast, the morning lowers,/And heavily in clouds brings on the day. Addison.

(logic) a statement that is necessarily true; "the statement ‘he is brave or he is not brave’ is a tautology"