Meaning

• (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.

Meaning

• Something that could happen, or could be the case, under different circumstances; a potentiality.