a chemical agent capable of reducing the surface tension of a liquid in which it is dissolved
the outer boundary of an artifact or a material layer constituting or resembling such a boundary
the extended two-dimensional outer boundary of a three-dimensional object
the outermost level of the land or sea
a superficial aspect as opposed to the real nature of something
on the surface
send via the postal service
the bags of letters and packages that are transported by the postal service
the system whereby messages are transmitted via the post office
a conveyance that transports the letters and packages that are conveyed by the postal system
