Basic Meanings:
* Cap: A covering for the head (hat)
* Capital: The top or head of something
* Captain: The leader of a group or team
Words with "cap" related to covering or containment:
* Capsule: A small, sealed container, often for medication
* Captivate: To hold someone's attention or interest
* Capacity: The amount something can hold
* Recap: To summarize or repeat something
* Encapsulate: To enclose or summarize something
Words with "cap" related to leadership:
* Captain: Leader of a team or group
* Captainship: The position of a captain
* Capitalize: To take advantage of an opportunity
* Capitalism: An economic system based on private ownership and free markets
Other words with "cap":
* Caprice: A sudden, unpredictable change in mood or behavior
* Capable: Having the ability or skill to do something
* Incapable: Lacking the ability or skill to do something
* Decapitate: To cut off the head
* Escape: To get away from something, often by using a method of hiding
Note: There are many more words with "cap" as a root, but this is just a starting point.