paralipsis (n.)

"pretended or suggested omission for rhetorical effect," 1580s, from Greek paraleipsis "passing by omission," from paraleipein "to leave on one side, pass over, leave untold," from para- "beside" (see para- (1)) + leipein "to leave" (from PIE root *leikw- "to leave"). As in passages that open with "not to mention," "to say nothing of," etc.