service

(noun): An act of being of assistance to someone.
(noun): The practice of providing such a service as economic activity.
(noun): A department in a company, an organization, a government department, etc.
(noun): A function that is provided by one program or machine for another.
(noun): The state of being subordinate to or employed by an individual or group
(noun): The military.
(noun): A set of dishes or utensils.
(noun): The act of initially starting, or serving, the ball in play in tennis, volleyball, and other games.
(noun): A religious rite or ritual.
(noun): The serving, or delivery, of a summons or writ.
(noun): (Israel, West Bank, also in Jordan, Lebanon and Syria) A taxi shared among unrelated passengers, each of whom pays part of the fare; often, it has a fixed route between cities.
(noun): A musical composition for use in churches.
(noun): Profession of respect; acknowledgment of duty owed.
(noun): The materials used for serving a rope, etc., such as spun yarn and small lines.
(verb): To serve.
(verb): To perform maintenance.
(verb): To inseminate through sexual intercourse
(verb): To perform a sexual act.

I say I did him a service by ending our relationship – now he can freely pursue his career.
Hair care is a service industry.
This machine provides the name service for the LAN.
Lancelot was at the service of King Arthur.
I did three years in the service before coming here.