n. A pit or chamber in the ground, or a cavity in a rock, or more rarely a warm air-tight structure above ground, for the storing of green crops for future use as fodder in the state called ensilage.To preserve in a silo; make silage or ensilage of.n. The pit silo has, in America, largely given way to above-ground structures of brick or stone or, commonly, of wood, these being found cheaper, equally effective, and more convenient except on hillsides. The wooden silo was at first rectangular, but for greater strength and to avoid the spoiling of silage in the corners a round form has been largely adopted. Round wooden silos are walled either with staves (see stave silo), or with studding lined and sheathed with boards or inside lathed and plastered with cement. The foundation in either case is of stone laid in cement. The superstructure may be sunk a short distance into the ground. Rectangular (and square) silos (preferred inside a rectangular building) are built with studding. All above-ground silos require doors, which are placed one above another and are often covered with an external shoot down which the silage falls as it is taken out. Outdoor silos usually require a roof with provision for ventilation.