Know (verb)

1. Be aware of through observation, inquiry, or information.
2. Be familiar or acquainted with a person, place, or thing.
3. Be certain or sure about something.
4. Have knowledge or information about a particular fact or situation.
5. Understand the nature or significance of.

Origin:

Old english cnāwan, of germanic origin; related to dutch and german kennen.

Examples:

1. I know that he is coming.
2. Do you know how to swim?
3. I just know it's going to rain tomorrow.
4. She knows all the latest gossip.
5. He knows how to play the guitar.