"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.
late 14c., "acting in conjunction, contributing to the same effect or event," from Old French concurrent or directly from Latin concurrentem (nominative concurrens), present participle of concurrere "to run together, assemble hurriedly; clash, fight," in transferred use, "to happen at the same time" (see concur). Related: Concurrency; concurrently.
Meaning "running together side by side" is from late 15c. Meaning "combined, joint" is from 1530s. In law, concurrent jurisdiction (that possessed equally by two courts and if exercised by one not usually assumed by the other) is recorded from 1767.