unit

noun:an individual thing regarded as single and complete but which can also form something larger or more complex
- The company is made up of several business units.
noun:a standard quantity used in measurement
- The meter is the basic unit of length in the metric system.
noun:a group of people working together as part of a larger organization
- The medical unit responded quickly to the emergency call.
noun:a piece of equipment or machinery that performs a particular function
- The air conditioning unit needs to be repaired.
noun:a section of a course or curriculum covering a particular topic
- We are studying a new unit on environmental science this week.