QUACK

I. intransitive verb Etymology: alteration of queck to ~, from Middle English queken, from queke, interjection, of imitative origin Date: 14th century to make the characteristic cry of a duck, II. noun Date: 1798 a noise made by ~ing, III. intransitive verb Etymology: 4~ Date: 1628 to act like a ~, IV. noun Etymology: short for ~salver Date: 1638 charlatan 2, a pretender to medical skill, ~ish adjective V. adjective Date: 1653 of, relating to, or used by ~s