Crux
* Crux: The essential point or heart of a matter.
* Crucial: Extremely important; vital.
* Crucify: To inflict death by nailing to a cross.
* Crucible: A severe test or trial.
* Excruciating: Intensely painful or agonizing.
Centr
* Central: Located in the middle or most important part.
* Centre/Center: The middle point.
* Centric: Relating to a center.
* Concentrate: To focus attention or effort.
* Eccentric: Deviating from the center; unusual.
Cor
* Core: The central part of something.
* Corrupt: Morally depraved; dishonest.
* Incorruptible: Not capable of being corrupted.
* Coronation: The act of crowning a monarch.
* Corpulent: Fat; obese.
Note: Some of these words might have slight variations in spelling depending on the region or dialect.