The extent to which a resource is used for the intended purpose; the ratio of useful work to energy expended.
A one-room apartment.
The extent to which time is well used for the intended task.
Capacity to do something well; technique, ability. Skills are usually acquired or learned, as opposed to abilities, which are often thought of as innate.
Great, excellent.
To know; to understand.
To have knowledge or comprehension; discern.
To set apart; separate.
To discern; have knowledge or understanding; to know how (to).
To have personal or practical knowledge; be versed or practised; be expert or dextrous.
To spend acquired points in exchange for skills.