Final answer:
The keyword used to define variables in a SAS Dataset is VARIABLE.
Step-by-step explanation:
The keyword used to define variables in a SAS Dataset is VARIABLE. It is used in the DATA step to define and name the variables that will be included in the dataset. For example:
DATA MyDataset;
VARIABLE Name Age Gender;
This code snippet defines a SAS Dataset named MyDataset with three variables: Name, Age, and Gender.