[chug] n [imit.] (1866): a dull explosive sound made by or as if by a laboring engine
[2]chug vi chugged ; chug.ging (1896): to move or go with or as if with chugs "a locomotive chugging along" -- chug.ger n [3]chug vt chugged ; chug.ging (ca. 1968): chugalug