early 15c., "to quarrel, brawl," also "mix up, present in disorder," from Anglo-French broiller "mix up, confuse," Old French brooillier "to mix, mingle," figuratively "to have sexual intercourse" (13c., Modern French brouiller), perhaps from breu, bro "stock, broth, brew," from Frankish or another Germanic source (compare Old High German brod "broth"), from PIE root *bhreu- "to boil, bubble, effervesce, burn." Compare Italian brogliare "to stir, disorder" (see imbroglio).