My DP says cats do not understand words, just tone of voice/voices they know. I think our cat definitely knows the following words, and he is wrong.
Her name
Dinner
Outside
Garden
Little num (what we call a treat)
No
In or out
Bye bye (if she has an inkling for staying in the garden at bedtime, bye bye is the final word that has her dashing in)
Sit (I have trained her to sit on command, using little nums. I grew up with dogs.)
Does your cat know words?