Early 20th century. From scientific Latin Ornitholestes, genus name from ancient Greek ὀρνιθο- + λῃστής robber, plunderer from ληΐθεσθαι to seize, carry off as booty (from ληΐς booty, plunder (from the same base as λεία booty, plunder, of unknown origin + -ις) + -ίζεσθαι, middle form corresponding to -ίζειν) + -της, suffix forming agent nouns.