In this work, an overall description of the phenomena known generically as lexical relations is developed, using methodology based on semantic functionalism. The phenomena described include polysemy, homonymy, synonymy, hyperonymy, cohyponymy, hyponymy and antonymy, with special attention being paid to polysemy or homonymy and in particular to synonymy and its relation to antonymy, parasynonymy and hyponymy. The theoretical basis of a research project on these relations is put forward, the main objective of which is to carry out a comprehensive analysis in a determined language of the semantic relations which constitute its basic units.