Game mechanics fall into several more or less well-defined categories, which (along with basic gameplay and theme) are sometimes used as a basis to classify games.

Each beast is of a different sort, and none seem to fit any well-defined categories.

Since there is no enumerated list of British black persons (even assuming that this is a well-defined category), speakers from the British black community cannot be systematically sampled from a range of social classes.

With the introduction of these and other products the market is beginning to segment into a number of well-defined categories.

There's no single camera that's good for everybody, even within their fairly well-defined categories.

But there are times when his affinity for a world of tidy, well-defined categories can undermine his reasoning.

Indeed, one of the volume's most profound insights is that rather than being an established, well-defined category, freedom was a terrain of conflict, whose meaning changed for blacks and whites alike during and after the Civil War.

Speaking of the difference between modern thought and ancient times, Richard Smith warns that even apparently well-defined categories "like 'race' can be confusing".

Certain "well-defined and narrowly limited" categories of speech fall outside the bounds of constitutional protection.

Other classes belong to less well-defined categories with respect to their role, though they may be even more ubiquitous.