* Synonyms are words with similar meanings. They replace each other in a sentence, but their grammatical function (noun, verb, etc.) remains the same.
* Grammatical function is determined by the word's role in a sentence. For example, "happy" is an adjective, "happily" is an adverb, and "happiness" is a noun. They all relate to the concept of joy, but their grammatical roles are distinct.
Example:
* "Big" (adjective) and "large" (adjective) are synonyms. They both describe size.
* "Run" (verb) and "sprint" (verb) are synonyms. They both describe the action of moving quickly on foot.
What can be confusing:
Sometimes, a word can be used as multiple parts of speech. For example, "run" can also be a noun (referring to a journey or a series of events). This doesn't mean that "run" is a synonym for a noun, but rather that it has multiple grammatical functions depending on the context.
Key takeaway:
Synonyms are words that have similar meanings, but their grammatical function is determined by their role in a sentence, not by their synonym relationship.