grouiller.

From Middle French grouiller (“to shake, stir, agitate, scold, hasten, swarm, teem, crawl”), from Old French grouiller (“to rumble”), alteration of Old French grouller (“to growl”), from Middle Dutch grollen (“to make a noise, rumble, growl, grunt, grumble, scold”), from Old Dutch *grullen, from Proto-Germanic *gruljaną, *graljaną (“to shout, make angry, provoke”), from Proto-Indo-European *gʰer- (“to rattle, make a noise, grumble”). Cognate with Middle High German grüllen (“to scorn, jeer”), Old English griellan (“to anger, provoke, vex”). More at grill. Alternate etymology derives sense of crawl from Frankish *grubilōn (“to dig, burrow, rummage, crawl”), from Proto-Germanic *grubilōną (“to dig, search, ponder”), from Proto-Indo-European *gʰrebʰ- (“to dig, scrape, scratch”). Cognate with German grübeln (“to brood over, mull over, speculate, ponder”), Old Norse grúfla (“to bend low, creep, crawl”). More at crawl.