The paper introduces a system of rules for description logic based formal representation of adjectives used in both attributive and predicative functions and involved in a variety of syntactic relations. The system was developed to convey the semantics of adjectives by virtue of concept and role constructors implemented in description logic formalisms known as SHOIN(D) and SROIQ(D). The system is intended to be integrated into a large-scale system of formalization rules devised for the development of description logic based definitions of domain terms. The proposed system of rules was tested and evaluated on two sets of syntactic units that contain attributive and predicative adjectives represented in English and Russian languages.