meow
The sound a cat makes, or to make that sound.
Meow is the sound a cat makes, and also the verb we use to describe a cat making that sound. When your cat wants food, attention, or just feels like chatting, she'll meow at you. Some cats meow constantly, while others stay mostly silent.
Cats use different meows to communicate different things. A short, quiet meow might mean “hello,” while a long, loud meow often means “I'm hungry!” or “Pay attention to me!” Scientists who study animal behavior have discovered that cats mostly meow at humans, not at other cats. Adult cats rarely meow at each other. They have learned that meowing gets results from people.
The word meow is an example of onomatopoeia, which means a word that sounds like what it describes, like “buzz” or “splash.” Different languages have their own versions: in Japan, cats say “nyan,” and in France they say “miaou.”
People sometimes say someone has a “catty” tone when they make mean or sarcastic remarks, but that's not really related to the actual sound cats make. Real meows are just cats trying to tell us something, usually that it's definitely, absolutely time for dinner.
As an interjection, meow! is what you might say to imitate a cat or to be silly.