They are words that have a similar meaning to another, they are used in Spanish to be used in texts with the aim of not repeating words and enlarging the discourse. They institute synonymous relationships that are essential in lexicographical analysis in order to fix definitions.
Synonyms not only enrich the language but also generate favoritism for one of the forms over the rest, causing them to fall into disuse and disappear. There are words that despite having similar meanings do not behave in the same way, here are the types of synonyms:
Full or strict synonyms: These have the same meaning in all linguistic contexts.
Partial or contextual synonyms: They have the same meaning in several but not all contexts and vary according to context and geography.
Referential synonyms: They do not mean the same thing but indicate common features.
Synonyms of connotation: they are terms that lose the true meaning.
They are words that have a meaning contrary to each other, they are part of the same grammatical category. There are three kinds of antonyms:
Gradual: The two words are progressively opposed. For example, cold and hot, because between them there is temperate and lukewarm.
Complementary: The meaning of one can exclude that of the other, that is, they are not compatible with each other
Reciprocal: They establish a relationship from the opposite point of view, they do not exist one without the other.