What words do my cats understand? All of them, I think! I talk to them constantly, in whole sentences.
Sometimes they talk back. Wimmy, especially, is famous for this. At night I'll turn off the lights and go to bed...pretty soon I'll hear..
"Mow-wow?" (I think that mean's "Mama?")
"Mow-wow....WOw??" (which I have interpreted to mean, "Mama, lost?"...in other words he's woken up in the dark and doesn't know where I am)...trust me...he's 5 1/2 years old and he's done this his whole life...they are very distinct syllables.
"No, Wim...mama's in beddy...come beddy with Mama?" (OK, so I speak 'Elmer Fudd' to my pets...it's not like they're going to have to go to a speech pathologist when they go to grade school) ...then you hear ...thump, thump, thump (you can actually hear a 16 pound Maine Coon walking across a wood floor very clearly) and then the bed shakes when he jumps up. He also has to tell me all about it when he's using the litter box...again starting the conversation off - "Mow-wow?"
Wimmy's actually the intelligence-challenged one. His sister Saint Pauli Girl Dark is much smarter. But Powdie has the largest vocabulary (she's 9)
"Cat check!" - this was one we used in the semi, to make sure she hadn't snuck out before we drove off...this means 'poke your head out and make sure the human knows where you are...very helpful to ensure somebody's not stuck in a closet before we leave for the day
"Daddy home" (she'll run and look out the window)
"No" "Naughty" "Stop that" and all variations on the theme...however, she pretty much ignores it when she feels like it (she may not have a middle finger but trust me, she can flip you off)
"Lay down" - stop stomping about on the body of the human and get comforable and settled in...also meant 'lay flat' on the dashboard of the semi so the driver could see over you.
She's also very good at conveying her wishes without resorting to spoken language.
***Stare*** ***Poke*** - "you ARE going to give me some of that chickie (or burrito, or any other spicy, tomato-based food she particularly loves), AREN'T you??"
**Knock things off the headboard onto the sleeping human's head and stare at them beligerantly when they get mad** - "It's time to get up and feed the cats"
She also has a really pissy meow that means, "Stop that!"...when you're brushing her or trying to move her somewhere she doesn't want to go (usually followed by a nip). She also uses it right before she smacks one of the other cats who come to close to her when she's sitting on Daddy's lap.
They're a bit spoiled...they're our kids.