"confusedly," 1570s, from Middle French pêle-mêle, from Old French pesle mesle (12c.), apparently a jingling rhyme on the second element, which is from the stem of the verb mesler "to mix, mingle" (see meddle). Phonetic French form pelly melly is attested in English from mid-15c.[pell-mell etymology, pell-mell origin, 英语词源]