Well in Java you can override methods as a part of it's polymorphism capabilities.
Basically what that means is let's say there is a class that does almost everything you need it to do but one method just does not quite work the way you need it. You can override that method and essentially extend that class and redefine that method in your own class.
You will hear this term usually associated with method overloading. Both method overloading and method overriding are parts of the polymorphism capability of Java.
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