A dependent feature is a feature that only makes sense when some other feature has a specific value. For example, in a database of motorvehicles 'number fo doors' is not meaningful if the type of vehicle is 'motorcycle'. Many {macine learning}} algorithms will perform more efficiently if they take into account this form of dependency, for exmaple, in a genetic algorithm it is not helpful to mutate features that cannot have any effect.
Defined on page 191
Used on page 191