Final answer:
The root word 'cap' means 'take' or 'seize', and it is common in English vocabulary, implying control or holding onto something, as seen in words like 'capture', 'capable', and 'capacity'.
Step-by-step explanation:
The meaning of the root word cap is 'take' or 'seize.' This root word is found in many English words and usually conveys the idea of grabbing, controlling, or holding onto something. For example, the word 'capture' is derived from this root and means to take control of or seize by force, while 'capable' suggests having the ability to seize or hold onto opportunities. Another word, 'capacity,' refers to the maximum amount that can be contained or held, which is a figurative way of 'seizing' or 'taking in' a certain quantity.