couth
/kuːθ/
(auxiliary verb, defective) To know how to; to be able to.
She can speak English, French, and German. I can play football. Can you remember your fifth birthday?
(modal auxiliary verb, defective) May; to be permitted or enabled to.
You can go outside and play when you're finished with your homework. Can I use your pen?
(modal auxiliary verb, defective) To have the potential to; be possible.
Animals can experience emotions.
(auxiliary verb, defective) Used with verbs of perception.
Can you hear that?.
To know.