One possible reason is that its not happy at that given moment.
I have heard that cats will purr when they are in extreme pain or very scared.
There is no illness that causes a cat to purr. Cats purr when they are happy, content, and socialized. This includes non domesticated cats.
This varies from cat to cat. I have had cats that don't purr at all and some that purr quite loudly. I would not be surprised if my current kitten purred at least 20 dB.
No, the word purr is a noun or verb, depending upon usage.An adjective is a word used to describe a noun.Examples:The cat made a soft purr as I stroked her.the noun purr is the direct object of the verb made;the adjective soft describes the noun purr.A contented cat will purr if you scratch its neck.will purr is the verb, what the cat does;the adjective contented describes the noun cat.
It "kneads the dough" this is a learned behavior. As a kitten is feeding it will "knead" so the milk will flow easier. They also purr when they're content another behavior learned from the mother. When kittens are born they are blind and deaf so the mother would purr and they would feel the vibrations and it would soothe them.
To say "the cat purred" would be an example of onomatopoeia. A cat would normally say "miaow" or "prrrr".
yes
Purr
Example sentence - When I pet my cat, he purrs contently.
Contentment in a cat.
cat
A massage chair.