What term describes land use that predates the current zoning ordinance and violates it?

The term that accurately describes land use that predates the current zoning ordinance and violates it is "nonconforming use." A nonconforming use refers to a property or land use that was legally established before new zoning regulations came into effect, making it incompatible with the current zoning classification. This means that while the existing use is not compliant with the updated zoning laws, it is still allowed to continue operating because it was in place prior to the changes in the ordinance.

Nonconforming uses are often protected to a certain extent to avoid punitive measures against property owners who were operating lawfully before the zoning laws changed. This protection is typically aimed at providing a reasonable level of security to property owners while allowing local governments to implement zoning regulations that reflect current land use objectives.

Other terms like "grandfathered use" can sometimes be used interchangeably with nonconforming use, but the more precise term in this context is "nonconforming use." The other options do not accurately capture the legal nuance associated with established uses that were in place before the current zoning laws, as "illegal use" implies a violation of the law from its inception, and "pre-ordinance use" lacks the legal acceptance typically associated with nonconforming uses.