There can be two types of semantic opposition: : the semantic opposition in meaning between the two stable polilexical units (SPUs) and the semantic opposition between the components of the SPUs. The semantic opposition of the components of the SPUs takes place when the components of two or more SPUs possess antonyms in their composition. Pairs of antonyms can be of bimembre and polimembre types. In this case, they contain the "track record" relationship of antonymy between the two pairs of SPUs, and of numerous SPUs. Phraseological antonyms are classified according to four types of semantic oppositions: 1. gradual, which designate the antonymic pairs of SPUs that express qualities, features, actions, circumstances in opposition of antonymy, possessing the intermediate notions; 2. complementary, which designate the antonymic pairs of SPUs without possessing the intermediate notions; 3. vector, which expresse actions, circumstances, features being in opposite directions, and 4. conversive - the antonymic pairs that express the bilateral relations, presents the same sense in different directions and with the differently placed accents. The motivation of SPUs in this case the following: only the SPUs that can express explicitly, without ambiguity the meaning of the message, but the monolexical synonym includes both polarizing semes into its structure; it leads to confusion in speech. In this case, only the context can „clarify” the situation. When the SPUs do not need the context, they are explicit and eliminate the ambiguous nature of their monolexical synonyms. For two phraseological units to be in antonymic relation it is necessary that they make a part of the same functional-semantic fields - objects, actions, qualities, circumstances - or be correlated to the same part of speech. [ABSTRACT FROM AUTHOR]