mass layoff

Definition from Nolo’s Plain-English Law Dictionary

For purposes of the WARN Act, a reduction in force that results in job loss or at least a 50% hours cut at a single employment site for (1) 500 or more employees, not including part-time employees, or (2) 50 to 499 employees, not including part-time employees, if at least 33% of the employer's active workforce are laid off.

Definition provided by Nolo’s Plain-English Law Dictionary.