the line or plane indicating the limit or extent of something

of, affecting, or being on or near the surface

come to the surface

(chemistry) a surface forming a common boundary between two things (two objects or liquids or chemical phases)

the bony part of the roof of the mouth

the upper surface of the mouth that separates the oral and nasal cavities

a surface forming part of the outside of an object

the apparent surface of the imaginary sphere on which celestial bodies appear to be projected