Kenneth G. Wilson (1923–). The Columbia Guide to Standard American English. 1993.
reiterate, iterate (vv.)
Commentators frequently argue in favor of a distinction that makes iterate mean “repeat” and reiterate mean “repeat again,” but most Standard users make no such distinction. Iterate is the rarer word, used primarily in scholarly and technical writing, where the distinction may indeed be in effect: The proof of the second example simply iterates the proof of the first. Reiterate is far more frequently used, and it usually means only “repeat,” whether once or many times: When she spoke again, she simply reiterated what she’d said once [many times] before. The one certain usage judgment: to reiterate again is unquestionably a tautology and must be avoided.
