environmentName

A unique name for the environment.

Constraint: Must be from 4 to 40 characters in length. The name can contain only letters, numbers, and hyphens. It can't start or end with a hyphen. This name must be unique within a region in your account. If the specified name already exists in the region, Elastic Beanstalk returns an InvalidParameterValue error.

If you don't specify the CNAMEPrefix parameter, the environment name becomes part of the CNAME, and therefore part of the visible URL for your application.