c.1600, from Latin obstreperus "clamorous," from obstrepere "drown with noise, make a noise against, oppose noisily," from ob "against" (see ob-) + strepere "make a noise," from PIE *strep-, said to be imitative (compare Latin stertare "to snore," Old Norse þrapt "chattering," Old English þræft "quarrel"). Related: Obstreperously; obstreperousness.