Third-party sexual harassment efers to a form of sexual harassment where the harasser is not an employee of the victim's organization but is a third party, such as a vendor, client, customer, or anyone with a business relationship with the company. This type of harassment can create a hostile work environment and negatively impact the victim's well-being and job performance.

Example
An employee at a retail store regularly faces inappropriate comments and advances from a customer who visits the store frequently. Despite the store's management being aware of the situation, they fail to address the issue or protect the employee from the customer's offensive behavior. This constitutes third-party sexual harassment, as the harasser is not an employee of the store but a customer.