This project has involved assembling a basic set of terms applicable to non-living membranes and membrane processes. The terms include the key vocabulary used in the literature concerned with scientific, technical and commercial aspects of the membrane field. Processes and membranes based on synthetic or modified natural polymers as well as ceramic and metallic membranes are covered. The resultant terms and their definitions represent a core set that will allow uniform understanding and eliminate most ambiguity or confusion caused by conflicting terminology now in use. The terms and definitions selected for inclusion reflect the majority preference of the membrane community. To avoid irreconcilable differences, definitions and descriptions involving interpretations of phenomena were minimized. Some terms were deleted in cases where majority preferences were not apparent. This strategy was adopted with the understanding that the current core group of terms, which enjoy majority support can be augmented as evolution of the field occurs.