Stakeholder Requirement (glossary)
(1a) The requirements for a system that can provide the services needed by users and other stakeholders in a defined environment. (ISO/IEC/IEEE, 2015, section 6.4.1)
(1b) The stakeholder needs and requirements definition process identifies stakeholders, or stakeholder classes, involved with the system throughout its life cycle, and their needs. It analyzes and transforms these needs into a common set of stakeholder requirements that express the intended interaction the system will have with its operational environment and that are the reference against which each resulting operational capability is validated. The stakeholder requirements are defined considering the context of the system-of-interest with the interoperating systems and enabling systems. (ISO/IEC/IEEE,2015)
Source
ISO/IEC/IEEE. 2015. Systems and Software Engineering -- System Life Cycle Processes. Geneva, Switzerland: International Organisation for Standardisation / International Electrotechnical Commissions / Institute of Electrical and Electronics Engineers. ISO/IEC/IEEE 15288:2015.
Discussion
Both definitions are taken from the introduction to the "Stakeholder Requirements Definition Process" in ISO/IEC 15288; there is no formal definition of the term "stakeholder requirement" in the standard.
For a full discussion of the role and importance of stakeholder requirements in systems engineering see the Stakeholder Needs and Requirements article.