During a two-day Royal Society meeting entitled \'Memory reactivation: replaying events past, present and future\' held at Chicheley Hall in May, 2019, we discussed and defined a set of terms for investigating and reporting in memory reactivations to facilitate a common language and thus simplifying comparison of results. Here, we present the results of the discussion and supply a set of terms such as reactivation and replay, for which the authors have reached a common consensus. This article is part of the Theo Murphy meeting issue \'Memory reactivation: replaying events past, present and future\'.