* Symbols represent meaning: Words, both spoken and written, are not the actual things they represent. They are abstract symbols that stand in for concepts, objects, actions, etc. For example, the word "cat" doesn't actually represent a cat, but it allows us to understand and communicate about the concept of a cat.
* Shared understanding: The meaning of a word is determined by a shared understanding within a community of speakers. This shared understanding allows us to use words effectively to communicate with each other.
* Arbitrary connection: The relationship between a word and its meaning is arbitrary. There's no inherent reason why the word "cat" refers to a feline creature. It's simply a convention that we all agree on.
Therefore, a system of spoken and written words fits the definition of a symbol system: a set of symbols with agreed-upon meanings that are used for communication and representation.