Reserve has 15 different meanings across 3 categories:
Noun · Verb · Proper Noun
an athlete who plays only when a starter on the team is replaced
"The coach called up the reserve player to finish the game after the starting guard got injured in the second quarter."
(medicine) potential capacity to respond in order to maintain vital functions
"The patient's heart rate remained stable despite the fever, indicating a strong physiological reserve."
a district that is reserved for particular purpose
"The national park serves as a protected reserve where hunting and logging are strictly forbidden to preserve the local wildlife."
armed forces that are not on active duty but can be called in an emergency
"The nation maintained a large reserve of trained soldiers who could be mobilized immediately if war broke out."
the trait of being uncommunicative; not volunteering anything more than necessary
"She has a natural reserve that makes her seem distant in large groups, rarely sharing her thoughts unless directly asked."
Restriction.
"The new traffic laws place strict reserves on how many vehicles can enter the city center during rush hour."
The act of reserving or keeping back; reservation; exception.
"He added a small reserve regarding his agreement to ensure no hidden conditions were overlooked."
In plain English: A reserve is something kept aside and not used yet, often as extra money for emergencies or an unused supply of resources.
"We need to book two tables at our favorite restaurant, so please make a reservation for eight o'clock tonight."
Usage: Use this noun to describe an official booking, such as holding a table at a restaurant, rather than the general idea of saving something for later. It is also commonly used in formal contexts to indicate a specific objection or limitation within an agreement.
hold back or set aside, especially for future use or contingency
"they held back their applause in anticipation"
give or assign a resource to a particular person or cause
"I will earmark this money for your research"
"She sets aside time for meditation every day"
To keep back; to retain.
"She decided to reserve some extra funds for an unexpected emergency."
A city in Kansas.
"The residents of Reserve, Kansas, celebrated their town's centennial parade last weekend."
The word entered English via Middle English and Old French as reservare, originally meaning to keep something back or set it aside. It derives directly from the Latin verb reservāre.