For building purposes or hazard evaluation here in california:
Fault Active - Fault Active - Active fault means a fault along which there has been displacement during the last 11,000 years.

Fault Inactive - Fault Inactive - Inactive fault means a fault along which there has been no major displacement for more than 3,000,000 years.

What the ones in between are? Just faults I guess.

And then here is a good summary taken from the California state division of Mines and Geology:
The evaluation of a given site with regard to the potential hazard of surface fault rupture is based extensively on the concepts of recency and recurrence of faulting along existing faults. In a general way, the more recent the faulting the greater the probability for future faulting (Allen, 1975). Stated another way, faults of known historic activity during the last 200 years, as a class, have a greater probability for future activity than faults classified as Holocene age (last 11,000 years), and a much greater probability of future activity than faults classified as Quaternary age (last 1.6 million years). However, it should be kept in mind that certain faults have recurrent activity measured in tens or hundreds of years whereas other faults may be inactive for thousands of years before being reactivated. Other faults may be characterized by creep-type rupture that is more or less ongoing. The magnitude, sense, and nature of fault rupture also vary for different faults or even along different strands of the same fault. Even so, future faulting generally is expected to recur along pre-existing faults (Bonilla, 1970). The development of a new fault or reactivation of a long-inactive fault is relatively uncommon and generally need not be a concern in site development.

Canie

• GUIDELINES FOR EVALUATING THE HAZARD OF SURFACE FAULT RUPTURE