Homonyms are words that have same form but have different unrelated meanings. A classic example of homonyms is Bank ( River Bank/ Financial Institute).
A related idea is that of homophones that refer to words that are pronounced in same way but different meaning or spelling of both (e.g., bear and bare).
Polysemes are words with related meanings. This linguistic phenomenon is called polysemy (lexical ambiguity).
Words having several sense are ambiguous and called polysemous. For e.g., word ‘chair’ can refer to a furniture or a person, act of presiding over a discussion etc.
In a particular use, only one of these meanings is correct.
Hyponymy is a word with most specific meaning. In the relationship between car & automobile. Car is a hyponym of automobile. The hypernym is a word with more general.
The word automobile is a hypernym for a car and a truck.
Antonym is a semantic relationship that holds between words that express opposite meanings
The word ‘Good’ is an antonym of ‘Bad’ and ‘White’ is an antonym of ‘Black’.
Word Synonym defines relationship between different words that have similar meaning.
Two words are synonyms in a context if they can be substituted for each other without changing the meaning of the sentence.