A term used to describe the formation of ions in the gas phase from a material deposited on a solid surface (known as an 'emitter') in the presence of a high electrical field. 'Field @D01620@' is an ambiguous term because it implies that the electric field desorbs a material as an ion from some kind of emitter on which the material is deposited. There is growing evidence that some of the ions formed are due to thermal @I03183@ and some to field @I03183@ of vapour evaporated from material on the emitter. Because there is generally little or no @I03183@ unless the emitter is heated by an @E01927@, 'field @D01620@' is a misnomer. The term is, however, firmly implanted in the literature and most users undertand what is going on regardless of the implications of the term. In addition, no better simple term has been suggested to take its place and so, reluctantly, it is recommended that it be retained.