The Act establishes definitions for terms used throughout the statutory framework. It defines autonomous vehicle (able to move autonomously for periods but requiring driver intervention), ‘‘driving’’ (including managing, controlling and, for autonomous vehicles, monitoring when moving autonomously, and riding bicycles), driving licences (Irish and foreign), EU roadworthiness certificate, Roadworthiness Directive and test certificate. It specifies ‘‘mechanically propelled vehicle’’ (including certain electrically assisted bicycles and partly electrical vehicles, but excluding tramcars and powered personal transporters), powered personal transporter (single‑person vehicle with prescribed weight, speed and power limits), pedal bicycle/tricycle (power and speed thresholds), and vehicle identification number (VIN).

The Act further defines regulatory categories and roles: owner, registered owner, vehicle insurer, vehicle guarantor, principal debtor, insured, public service vehicle (large and small), omnibus, street service vehicle, parking/place/use, road/public road/roadway/footway, road authority, hire‑drive agreement, appointed stand/weighbridge and mobile weighbridge, and disqualification orders (cross‑referenced to specified sections). It clarifies that ‘‘contravenes’’ includes refusal or failure to comply, references to the Rules of the Road mean the Minister’s publication, a substantially disabled vehicle by collision remains a mechanically propelled vehicle for the Road Traffic Acts 1961–2010 but not for other purposes, drawn vehicle excludes animal‑drawn vehicles, and use with consent includes implied consent.