The meaning of the word indivisible is to be "unable to be divided or separated".
To be indivisible is to be unable to be divided by another number exactly without leaving a remainder.
Something indivisible cannot be broken up or divided and it's rock solid.
The most common use of the word indivisible is in the Pledge of Allegiance, where it is used to show how our country is united and can't be broken up.
But you can use the word indivisible for any group or organization that seems indestructible.
Some other words for indivisible are words such as unbreakable, permanent, inseparable, impenetrable, joined and Unified.
In Elementary School we used to say the Pledge of Allegiance and said the word Indivisible and at the time of saying the Pledge of Allegiance I never really knew what teh word Indivisible meant.