When cats meow, there’s a one-to-one correspondence between the aural qualities of the sound and the communicative intent of the cat—the same meow doesn’t have different meanings depending on the preceding and following meows. That’s how animals normally use sounds to communicate.

There are two common exceptions, where animals string arbitrary sounds together in longer sequences in which the individual components don’t have distinct communicative intents in the way animals usually interpret them: songbirds and humans. (Another possible exception might be cetaceans.)

(For example: If I said “pass the butter”, “don’t eat all the butter”, or “I need to get more butter”, the word “butter” would have different communicative intents even if I said them the exact same way—like a note of a bird’s song, and unlike a cat’s meow.)