The development of definitions is an integral part of the research process but is often poorly described. This paper details the iterative development of five definitions: Policy, Health policy-maker, Health policy agency, Policy documents, and Research findings. We describe the challenges of developing definitions in a large multidisciplinary team and the important methodological repercussions. We identify four factors that were most helpful in this process: (1) An emphasis on fit-for-purpose functionality, (2) Consultation with in-context experts, (3) Our willingness to amend terms as well as definitions, and to revisit some methods and goals as a consequence, and (4) Agreement that we would satisfice: accept 'good enough' solutions rather than struggle for optimality and consensus.