Final answer:
An agency coupled with an interest is a special agency relationship where the agent has a personal, often financial interest in the subject of the agency, which prevents the principal from unilaterally terminating the relationship.
Step-by-step explanation:
A agency coupled with an interest is an exception to the rule that says that either the principal or the agent may terminate an agency relationship at any time. This is a special type of agency relationship in which the agent has a personal interest in the subject of the agency, separate from that of the principal's interest. This personal interest is often a security interest in the property being dealt with, which gives the agent a right to protect their own interest, making it impossible for the principal alone to terminate the agency.
For example, if an agent lends money to a principal and takes as security an interest in the goods that the agent is selling on behalf of the principal, the agent has an agency coupled with an interest. The agent has the right to sell the goods to recoup the loan, and thus cannot be prematurely removed from their position by the principal.