base basement basis bearing wall bed bedding bedrock belly best bottom bottom side bottommost breech buttocks cut deepest downside floor flooring fond footing foundation fundament fundamental giveaway ground grounds groundwork half-price hardpan lower side lowest lowest layer lowest level marked down nether side nethermost nethermost level pavement principle radical reduced riprap rudiment sacrificial seat sill slashed solid ground solid rock stereobate stylobate substratum substruction substructure terra firma underbelly underbuilding undercarriage undergirding underlayer undermost underneath underpinning underside understruction understructure