What is define include?

"Define include" is not a commonly used phrase in programming. However, there are two different concepts that could potentially be related to this phrase:

1. The #include directive is a preprocessor directive in C and C++ that instructs the compiler to include a specified header file at the location of the directive. This is often used to make external libraries or other functions available to the main program.

2. In some programming languages, "define" is used to declare a constant value or macro that can be used throughout the program. These values can also sometimes be included in header files using the #define directive.

It is possible that "define include" could refer to the combination of these two concepts - defining constants or macros in header files that are then included in a program using #include directives. However, this is not a commonly used phrase in programming and would likely need to be clarified in context.