Agile

agile is made up of ag- meaning "to do" and the Latin suffix -ile which means "pertaining to; like; having the character or quality of." Thus, agile means "having the quality of doing or acting" or "able to do or move quickly and easily; nimble."
Peter is agile and athletic.
A word based on agile is agility, meaning "the ability to move quickly and easily."
The quarterback had remarkable agility.

Agent

agent comes from ag- meaning"to do" plus the Latin suffix -ent which means "a person who." Thus, agent means "a person who does something." This word is applied to someone who does a specific action or job, or who works for or represents an individual, company, or government bureau.

He is an FBI agent.
Does the actor have a press agent?
Does that company have a sales agent in our town?

A word based on agent is agency, meaning "a company, department or bureau that does a specific job or that represents other people or companies."

She works for an employment agency.

Agenda

agenda comes directly from a Latin word based on ag- meaning "to do" and means "a list of things to be done; a list of things to be discussed or decided upon."
There were three items on the agenda for the business meeting.

Root: Ag-, Act-

The Latin ag- or act- means "to do; drive". This root forms some of the most frequently used words in the English Language. You already know some common words based on it, such as act or action. Here are seven more core words based on the root ag- or act- that tou should know: agenda, agent, agile, active, actor, actual, enact.