العرضي - أعني الخاصة والعرض العام - ينقسم إلى لازم ومفارق.
The extrinsic predicables—property and common accident—are divided into necessary and separable accidents.
A necessary accident (lāzim) cannot be separated from its subject under the relevant consideration.
For example, being even necessarily belongs to the number four. Evenness is not the defining meaning of 'four', but the number four cannot fail to be even.