(linguistics) The apparent etymology of a term based on components occurring in the modern form of the language, such as earth + -en for earthen, which actually occurred in Old English as eorthene.

(physics) An abstract boundary, of constant energy, useful for predicting the thermal, electrical, magnetic, and optical properties of metals, semimetals, and doped semiconductors.

plural of surface area

(geometry) The total area on the surface of an object. / (computing) The total resources of a system that are accessible from the outside world and thus might be attacked.

Any n-dimensional surface (or line) having a constant scalar potential

plural of developable surface

plural of heating surface

Synonym of beneath the surface

(idiomatic) Beyond what is obvious.

plural of Riemann surface