Reference

Medical device regulatory glossary

Plain-English definitions of the terms that come up in FDA device classification, 510(k) predicate searches, and EU MDR and UK market access — written for medical device start-ups, digital health and SaMD teams, and medtech manufacturers. The United States, European Union and United Kingdom are kept separate because they classify and route devices differently. Each term links to its official regulator source, opening in a new tab.

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United States — FDA

FDA classifies devices by risk and routes them through premarket notification, De Novo or approval. Product codes and K-numbers are the practical keys to everything else.

510(k)(opens official source in a new tab): A premarket notification submitted to FDA showing a device is substantially equivalent to a legally marketed predicate device. Most Class II devices reach the US market this way; the outcome is clearance, not approval.
510(k) exempt(opens official source in a new tab): Device types FDA has exempted from premarket notification, mostly Class I and a limited set of Class II. Exempt devices still follow general controls such as registration, listing, labelling and (usually) quality system requirements.
Abbreviated and Special 510(k)(opens official source in a new tab): Alternative 510(k) formats. A Special 510(k) covers a manufacturer's own modification to its cleared device; an Abbreviated 510(k) relies on recognised standards or guidance to support equivalence.
Artificial Intelligence-Enabled Medical Devices(opens official source in a new tab): FDA's hub for AI-enabled device submissions: transparency for adaptive algorithms, the publicly published list of AI-enabled devices, and lifecycle management expectations such as Predetermined Change Control Plans.
Augmented Reality and Virtual Reality (AR/VR)(opens official source in a new tab): Devices presenting AR/VR content for diagnosis, treatment planning or training. FDA reviews them under the normal device pathways, with extra attention to human factors, image quality and the claimed clinical use.
De Novo(opens official source in a new tab): A request for FDA to classify a low-to-moderate risk device that has no suitable predicate. A granted De Novo creates a new classification and product code that later devices can use as a predicate.
Device class (I, II, III)(opens official source in a new tab): FDA's risk-based classes. Class I is low risk under general controls, Class II needs special controls and usually 510(k) clearance, Class III is high risk and generally requires PMA.
Indications for use vs intended use(opens official source in a new tab): Indications for use state the disease or condition, patient population and use conditions on the label. Intended use is the broader objective a manufacturer claims; both shape classification and predicate choice.
K-number(opens official source in a new tab): The identifier FDA assigns to a 510(k) submission, such as K243438. Predicate devices are cited by K-number, so it is the key to looking up a clearance in FDA's public databases.
Medical Devices that Incorporate Sensor-based Digital Health Technology(opens official source in a new tab): Devices using wearables and other sensor-based digital health technology to collect physiological data. FDA guidance on these devices sets specific performance goals and addresses interoperability considerations.
MQSA National Statistics(opens official source in a new tab): FDA's published statistics on mammography facility inspections and compliance under the Mammography Quality Standards Act — useful context when assessing devices in the mammography space.
PCCP (Predetermined Change Control Plan)(opens official source in a new tab): An FDA-authorised plan describing changes a manufacturer may make to a cleared or approved device — commonly used for AI/ML software — without a new submission each time.
PMA (Premarket Approval)(opens official source in a new tab): The most rigorous FDA route, required for most Class III devices. It requires valid scientific evidence, usually including clinical trials, that the device is safe and effective.
Predicate device(opens official source in a new tab): A legally marketed device used as the comparison in a 510(k). A strong predicate shares the intended use and has similar technological characteristics; recent clearances in the same product code are the usual starting point.
Product code(opens official source in a new tab): A three-letter FDA code identifying a device type in the FDA Product Code Classification Database. It links the device to its regulation number, class, review panel and applicable guidance.
Q-Submission / Pre-Sub(opens official source in a new tab): FDA's interactive feedback programme. A Pre-Submission lets a sponsor ask FDA about classification, pathway, predicate choice or a test plan before filing.
Regulation number (21 CFR)(opens official source in a new tab): The section of Title 21 of the Code of Federal Regulations that defines a device type and its class, for example 21 CFR 870.2800. Every product code maps to a regulation number.
SaMD (Software as a Medical Device)(opens official source in a new tab): Software intended for a medical purpose that is not part of a hardware device. FDA classifies it by risk and usually routes it through 510(k) or De Novo; in the EU it is medical device software assessed under MDR Rule 11.
Substantial equivalence(opens official source in a new tab): The 510(k) standard: the new device has the same intended use as the predicate and either the same technological characteristics, or different ones that raise no new questions of safety and effectiveness.

European Union — EU MDR

The EU assesses conformity under MDR 2017/745, usually with a Notified Body, and the result is CE marking. Classes and evidence expectations differ from the FDA equivalents.

Authorised Representative (EC REP)(opens official source in a new tab): An entity established in the EU that a non-EU manufacturer appoints to carry defined legal duties under MDR. The UK has a parallel but separate role, the UK Responsible Person.
CE marking(opens official source in a new tab): The mark showing a device meets EU requirements and may be placed on the EU market. It follows a conformity assessment — involving a Notified Body for anything above Class I — and is not equivalent to FDA clearance.
Classification rules (Class I, IIa, IIb, III)(opens official source in a new tab): MDR Annex VIII rules assign a class from duration of contact, invasiveness, active function and intended purpose. EU class does not map one-to-one onto FDA classes: a US Class II device may be EU Class IIa, IIb or III.
Clinical evaluation and CER(opens official source in a new tab): The systematic appraisal of clinical data demonstrating safety and performance, documented in a Clinical Evaluation Report and updated through the product's life.
EU Declaration of Conformity(opens official source in a new tab): The manufacturer's signed statement that the device meets MDR requirements. It accompanies CE marking and names the applicable class, conformity route and Notified Body where relevant.
EU MDR 2017/745(opens official source in a new tab): The EU Medical Device Regulation governing classification, conformity assessment, clinical evidence, labelling and post-market obligations for devices sold in the EU.
EUDAMED(opens official source in a new tab): The EU database for devices, economic operators, certificates, clinical investigations and vigilance, tied to UDI registration.
MDSW and Rule 11(opens official source in a new tab): Medical device software under MDR. Rule 11 classifies software providing information used for diagnosis or therapeutic decisions as at least Class IIa, and higher when serious deterioration or death could result — often stricter than the US reading of the same product.
Notified Body(opens official source in a new tab): An organisation designated by an EU member state to audit a manufacturer's quality system and technical documentation. There is no equivalent third-party gatekeeper in the FDA 510(k) route.
Technical documentation (Annex II / III)(opens official source in a new tab): The MDR dossier describing the device, design, verification, risk management, clinical evaluation and post-market surveillance plan.
UDI-DI(opens official source in a new tab): The Unique Device Identification device identifier used for traceability and EUDAMED registration. FDA operates its own UDI system with the GUDID database.

United Kingdom — UK MDR and MHRA

Great Britain runs its own framework with UKCA marking and Approved Bodies overseen by MHRA, while Northern Ireland continues to follow EU rules.

Approved Body(opens official source in a new tab): The UK counterpart to an EU Notified Body, designated to assess conformity for UKCA marking in Great Britain.
MHRA(opens official source in a new tab): The Medicines and Healthcare products Regulatory Agency, the UK regulator responsible for device registration, market surveillance and vigilance.
Northern Ireland and CE recognition(opens official source in a new tab): Northern Ireland continues to follow EU rules, so CE marking applies there while Great Britain runs the UKCA route. Great Britain also continues to accept CE-marked devices during the current transition arrangements.
UK MDR 2002(opens official source in a new tab): The UK Medical Devices Regulations 2002 (as amended), still the operative UK framework and based on the older EU directives rather than EU MDR — one reason UK and EU classification can differ.
UK Responsible Person (UKRP)(opens official source in a new tab): A UK-based entity a non-UK manufacturer must appoint to register devices with MHRA and act as its point of contact.
UKCA marking(opens official source in a new tab): The Great Britain conformity marking. It signals compliance with UK rules and is separate from CE marking, so a device may need both routes to cover the UK and the EU.

Cross-cutting terms

Concepts that apply in all three systems, even where the documentation and thresholds differ.

Clinical evidence(opens official source in a new tab): Data supporting safety and performance. FDA often accepts bench and comparative data for 510(k), while EU MDR generally expects clinical data proportionate to class and novelty.
Intended purpose(opens official source in a new tab): What the manufacturer claims the device does, as stated in labelling and promotional material. It drives classification, pathway and evidence in all three systems.
Post-market surveillance and vigilance(opens official source in a new tab): Ongoing monitoring and reporting of device performance and incidents — MDR PMS/PSUR obligations, MHRA reporting in the UK, and FDA medical device reporting in the US.
QMS (ISO 13485)(opens official source in a new tab): The quality management system standard for medical devices, expected under EU MDR and UK rules and largely aligned with FDA's Quality System Regulation.
Risk management (ISO 14971)(opens official source in a new tab): The standard for identifying hazards, estimating and controlling risk, and monitoring control effectiveness across the device life cycle.

Informational only — not legal or regulatory advice. Definitions are simplified summaries and requirements change. Always confirm classification, pathway and market requirements with the FDA, the relevant EU Notified Body / MHRA, and qualified regulatory counsel.