1. Real Definition. The articulation of the essence of a thing either directly (by reference to the essence itself) or indirectly (by reference to the thing’s material cause, efficient cause, final cause, effects, properties, or accidents).   Classically, real definitions were also sub-divided into those which are metaphysical (through genus and specific difference) and physical (through causes).  A real definition through properties, effects, or accidents is sometimes referred to as “descriptive” definitions, especially in the case of definitions through accidents.  2. Nominal Definition. The articulation of the meaning that a word or phrase has for a particular linguistic community.