A more thorough explanation:

A whipsaw strike is a type of strike where workers strike against some but not all members of a multiemployer association. The purpose of this strike is to pressure all the employees to negotiate a labor contract. Employers whose workers are not on strike have the right to lock out employees to exert counterpressure on the union.

For example, if a union is negotiating with a group of employers who are part of an association, the union may call for a whipsaw strike against only some of the employers to put pressure on all of them to negotiate a labor contract.

This type of strike is different from a general strike, which is organized to affect an entire industry, or an economic strike, which results from an economic dispute with the employer.