According to the Capability in Business Analysis™ (CCBA®) guidelines, a derive traceability relationship is one where a requirement is derived from another requirement, typically from a higher level to a lower level12.
A functional requirement to provide a user login screen is an example of a derived requirement, as it is derived from a stakeholder requirement for an online system. A derived requirement is not explicitly stated by the stakeholder, but is necessary to satisfy the stakeholder requirement.
References: The CCBA® learning documents, which can be found on the IIBA website12, describe the various types of traceability relationships that a business analyst can use to understand and manage the requirements, including the derive relationship. Additionally, the IIBA Bookstore offers resources that provide further insights into the objectives and best practices for business analysis, including the use of traceability matrix345.