Describe the concept of synonymy.

**Synonymy** refers to the relationship between words or expressions that have similar or identical meanings. Synonyms are words that can often be used interchangeably in specific contexts without changing the overall meaning of a sentence. For example, "happy" and "joyful" are synonyms because they both convey a sense of positive emotion.

However, while synonyms share similar meanings, they may have subtle differences in connotation, usage, or context. For instance, "happy" and "ecstatic" both describe positive emotions, but "ecstatic" implies a more intense feeling than "happy." Understanding synonymy helps in choosing the most appropriate word for a given context and in grasping the nuances of language.