A single contract for group medical insurance issued to an employer is known as

While "group policy" refers to the insurance coverage that extends to a group of individuals, it does not specifically denote the single contract issued to the employer. Instead, the term "group policy" is often used to describe the overall insurance arrangement rather than the formal documentation itself, which is classified as a master policy.

The term "employer policy" is not standard terminology in the insurance industry. While it may imply a policy held by the employer, it does not specifically describe the contractual nature of the arrangement or the group aspect of the coverage provided to employees, leading to potential confusion.

A certificate policy is a document provided to individual members of the group, summarizing their coverage under the master policy. It is not the primary contract itself but rather a certificate that confirms the insurance benefits afforded to each employee, making it an incorrect choice for describing the single contract issued to the employer.