Definitions of reserve:

• noun:   the trait of being uncommunicative; not volunteering anything more than necessary
• noun:   something kept back or saved for future use or a special purpose
• noun:   (medicine) potential capacity to respond in order to maintain vital functions
• noun:   formality and propriety of manner
• noun:   armed forces that are not on active duty but can be called in an emergency
• noun:   a district that is reserved for particular purpose
• noun:   an athlete who plays only when another member of the team drops out
• verb:   hold back or set aside, especially for future use or contingency
• verb:   arrange for and reserve (something for someone else) in advance

  Example: "Reserve me a seat on a flight"

• verb:   obtain or arrange (for oneself) in advance

  Example: "We managed to reserve a table at Maxim's"

• verb:   give or assign a share of money or time to a particular person or cause