Mine go from one extreme to the other.  Demi doesn't even know her name!
Bandit, however, not only knows the word "tuna" she understands it when DH
and I *spell* t-u-n-a (we tried that trick in order to talk about it without
Bandit running up and begging, ha!).

She also knows...

"Bandit want the brushing?"  - she runs up to me and starts purring even
before I get the brush out.

"Come huggers me."  - she come and snuggles next to me so I can hug her to
my chest like a teddy bear at night.

"Kitty, kitty hungry?" - she runs and waits at the place I put her saucer
down.

"Go lay down!" - she knows she's getting a "time out" and goes into my
bedroom, usually to lay down on my bed, but sometimes she will sit right in
the doorway and stretch her neck out to look at us until we let her come
out.

"Bandit want the bugga belly?" - she growls and tries to run away before I
can grab her, put her on her back, stick my face in her belly and shake my
head back and forth while murmuring, "bugga, bugga, bugga" - she pretends to
hate this, but she secretly likes it.

"Gimme some gitchee belly!" - she rolls over onto her back so I can
"gitchee" her belly with my hand.

There are several other things she understands too, but you get the gist!

Hugs,

CatNipped

Both cats:
Are you HUNGRY?
Do you want a  TREAT?
Do you want to go OUTSIDE?
OTIS
CHESTER

Otis:
You're such a GOOD BOY
You're so HANDSOME
Time for BED
COME
BAD CAT (he redoubles his efforts at whatever he is doing)
IT'S OKAY

Chester:
Do you want a BRUSH?
Where's your TOY?
NO!!!!

That's all I can think of right now,

Susan M
Otis and Chester
Bilingual cats

<SNIP>

Both kittens know their names... They understand:
FOOD, SNACK, HUNGRY, OUTSIDE, GET DOWN,
STOP, SORRY (used when giving meds), BEDTIME, and various other phrases...
Sometimes when I talk to them they get the funniest look on their face....?
Perhaps contacting the mothership for translation?
Mathew
Butler to 2 kittens: Chablis & Muscat
En Vino Veritas

It's a little hard to tell, since "understanding" and
"acting upon" are different things, to a cat!   (I know
Melisande understands things like "NO!" and "Get off of
there - NOW!"  it doesn't mean she pays any attention to them.)

Ours know lots of words.

Everyone knows their name...

they know food of course
and "some," which means "do you want some treats?"
Smokey knows "sandwich" and "pizza"

They know and fear "clip claws"
and "PSSSST BAD!"

They know "bed/bye"  and "up" (up into bed)

Such literate kitties!

--Fil

They all know Food, and Roxie knows Ham, her favorite treat. Because we
rarely give the kids people food, we've had to come up with creative
substitutes for that word, such as using the scientific name for pig or
using foreign words for pig or ham.

The best one is the Hog Call, which only Stosh responds to. I used it with
Fritzie when we lived in the suburbs, and he'd come running from blocks
away. It's something like "KitTTTTEEEEEEkittykitty-
kittykittykittykitTEEEEEEEEEEEEEEEEE!!!" I wonder if it's a guy thing
because none of the girls come for it. Long ago in Fritzie's youth I'd have
neighbors screaming out their windows for me to shut the **** up, it's that
bad. I'd heard there is an annual hog-calling contest, and I've seriously
thought about taking it on the road.

Blessed be,
Baha

Persia knows her name (I think she knew it before I did!)
She knows "Wanna get brushed?"
She knows "Time to go to sleep" and "Come sleepy with momma!"
She knows NO! or a stern UH-UH!
She knows "Kitty Treat?" but she can't have them anymore :(
She knows "Kitty Walk?" when the weather is nice enough for me to put her in
the Kitty Walk enclosure.
She knows "Not time yet" when it's not time for me to get out of bed.
Ditto "Not time yet" when she's begging for food right after she finished
her morning bowl of kibble and doesn't get more until late afternoon (but
you can't blame a gal for trying!)
I think all cats understand FOOD.  She doesn't get tuna (hates it) so she
doesn't know specific food names.

I'm sure there's more; I never actually counted them.  Persia's a bright
gal.

Jill

My Punkers comes every evening and reclines on my chest as I recline on
the couch watching telly.  Her most favorite thing in the whole world
is when I massage her ears.  Her eyes close, mouth goes limp and her
body just melts!  She always looks rather embarresed when she comes out
of it with a start. :)  Another thing I do is talk to her softly and
say how soft she is, how beautiful, how much I love her little pink
nose.....  This sends her into a full blown snit!  She slits her eyes
and glares at me, lashes her tail, and goes off in a huff.  What on
earth does she imagine I'm saying to her??!  Why does she react like
that?  Curious.  PatM

I'm sure Shmogg understands abolutely everything I say to him. He just
doesn't give a rat's arse, thats all.

IBKFergus, on the other hand, makes me wonder if there's anything going on
in that fuzzy little head of hers at all.

Yowie

As to 'How many words she understands'....My answer  to this is .Only 'What'
she wants to hear..concerning her own comfort !!...All else is a 'Foreign'
language to her ....LOL....