Plow  (us plow) —n. 1 implement for cutting furrows in the soil and turning it up. 2 implement resembling this (snowplough). 3 (the plough) the great bear (see *bear2) or its seven bright stars. —v. 1 (also absol.) Turn up (the earth) with a plough. 2 (foll. By out, up, etc.) Turn or extract with a plough. 3 furrow or scratch (a surface) as with a plough. 4 produce (a furrow or line) thus. 5 (foll. By through) advance laboriously, esp. Through work, a book, etc. 6 (foll. By through, into) move violently like a plough. 7 colloq. Fail in an examination.  plough back 1 plough (grass etc.) Into the soil to enrich it. 2 reinvest (profits) in the business producing them. [old english]