We don't know if our correspondent was teasing, but one of the two-plus answers to his double definition question is found in the first part of his two-part question. Got that? Another, less confounding way to put it is this: the original definition of tautology names "the needless or meaningless repetition in close succession of an idea, statement, or word." The Greek-based combining form taut- means "the same"; the Greek logos means "word."

Appropriately enough, tautology is not the only term in our language to name a meaningless repetition. Pleonasm also serves that purpose. With its origin in the Greek "to be excessive," pleonasm names "the coincident use of a word and its substitute for the same grammatical function"; or, more broadly, "the use of more words than those necessary to denote mere sense."

As if tautology and pleonasm weren't enough, our language also provides a third term for needless repetition, this one from Latin. Redundancy has its roots in the Latin "to overflow; to be in excess."