thin structure composed of a single thickness of cells | the outer boundary of an artifact or a material layer constituting or resembling such a boundary |
a hen that lays eggs | a device that provides reactive force when in motion relative to the surrounding air; can lift or control a plane in flight |
single thickness of usually some homogeneous substance | a superficial aspect as opposed to the real nature of something |
an abstract place usually conceived as having depth | information that has become public |
a relatively thin sheetlike expanse or region lying over or under another | the extended two-dimensional outer boundary of a three-dimensional object |
| the outermost level of the land or sea |