The Act's definitions and interpretative provisions establish terms and references used throughout. It defines key terms including Appeals Tribunal (the Irish Financial Services Appeals Tribunal), appointed/ex‑officio members of the Commission, associated entity (holding company, subsidiary, sibling subsidiary, >20% beneficial entitlement, partnership/joint venture), approved stock exchange, Bank (Central Bank of Ireland), Capital Requirements Regulation (Regulation (EU) No 575/2013 with numerous listed amendments), Central Bank Acts, Commission (Central Bank Commission), Governor (including acting Governor and Head of Central Banking), Heads of Function, Minister (Minister for Finance), Financial Services and Pensions Ombudsman, financial services/providers, voting rights and related terms.

The Act also sets interpretative rules: references to enactments include subsequent amendments; section/subsection references default to this Act; specified ‘‘designated enactments’’ and ‘‘designated statutory instruments’’ include an extensive list of EU Regulations, Delegated and Implementing Regulations, the SSM and SRM instruments and other named measures; a function or power under the Act is not limited by implication; ‘‘directors’’ for entities without a board means persons directing operations; references to regulated financial service providers include persons who were regulated at the relevant time.