Final answer:
The word 'int' can be omitted from variable definitions utilizing generic types where the specific type can be inferred by the compiler, but this cannot be applied to the primitive 'int' type itself, where an explicit declaration is required.
Step-by-step explanation:
The word int can be omitted from a variable definition for any datatype except for an int itself. This is specifically applicable in languages like Java, where int is a primitive data type used to declare variables that can hold integer values. For instance, when using generic types, such as in a templated class or method, one can use type inference to omit the specific type when it can be inferred by the compiler. However, this is not applicable to primitive data types like int; you must explicitly declare the type.