Merriam-Webster Collegiate Dictionary - manure

 I. transitive verb  (~d; manuring)  Etymology: Middle English manouren, from Anglo-French mainouverer, meinourer to till (land), construct, create, from Medieval Latin manu operare to perform manual labor, from Latin manu by hand + operari to work — more at operate  Date: 15th century  1. obsolete cultivate  2. to enrich (land) by the application of ~  • ~r noun  II. noun  Date: 1532 material that fertilizes land; especially refuse of stables and barnyards consisting of livestock excreta with or without litter  • manurial adjective