Reference
Medical Device Glossary 2026
A plain-language reference of the terminology and regulatory concepts that shape the medical device industry. Built for clinicians, biomedical engineers, and MedTech teams who need a shared vocabulary.
Device classification
Medical devices are grouped into risk tiers. The tier determines what regulatory controls apply, what documentation is required, and how the device reaches market.
- Class I
- Lowest-risk devices — subject to general controls. Examples include bandages, tongue depressors, and examination gloves. Most are exempt from premarket notification.
- Class II
- Moderate-risk devices — typically require premarket notification to demonstrate substantial equivalence to a predicate device. Examples include infusion pumps, surgical drapes, and most imaging devices.
- Class III
- Highest-risk devices — sustain or support life, are implanted, or present potential unreasonable risk. Require premarket approval with clinical evidence. Examples include heart valves and implantable defibrillators.
Regulatory pathways
The pathway a device takes to market depends on its classification and novelty. Most moderate-risk devices follow a shorter pathway; genuinely new or high-risk devices follow a longer one.
- 510(k)
- A premarket notification demonstrating substantial equivalence to a legally marketed predicate device. The dominant pathway for Class II devices.
- PMA
- Premarket Approval — the pathway for Class III devices, requiring clinical evidence of safety and effectiveness.
- De Novo
- A classification pathway for novel devices of low-to-moderate risk that do not have a predicate.
- HDE
- Humanitarian Device Exemption — a pathway for devices addressing rare conditions that affect small populations.
Device identification
Every commercially distributed device carries a standardized identifier. Identifiers make it possible to track devices through supply chains, hospital inventories, and adverse-event reporting.
- UDI
- Unique Device Identifier — a standardized identifier required for every commercially distributed medical device. Composed of a device identifier (DI) and a production identifier (PI).
- DI
- Device Identifier — the portion of the UDI that identifies the device model and its labeler.
- PI
- Production Identifier — the portion of the UDI that identifies production-specific attributes such as lot number, serial number, or expiration date.
- GMDN
- Global Medical Device Nomenclature — an international coding system for generically identifying medical devices independent of brand or manufacturer.
- GUDID
- Global Unique Device Identification Database — a reference registry of UDI records for commercially distributed medical devices in the United States.
Safety monitoring
After a device enters the market, ongoing safety monitoring captures adverse events, malfunctions, and recalls. This post-market surveillance is distinct from the pre-market approval process.
- Adverse event
- An injury, death, or serious malfunction potentially associated with a medical device. Reportable by manufacturers, user facilities, and healthcare professionals.
- Recall (Class I)
- A recall for a device that has a reasonable probability of causing serious adverse health consequence or death.
- Recall (Class II)
- A recall for a device that may cause temporary or medically reversible adverse health consequence.
- Recall (Class III)
- A recall for a device that is not likely to cause adverse health consequence.
Documentation
Every device is accompanied by documentation that guides safe use. This documentation is as regulated as the device itself.
- IFU
- Instructions for Use — the manufacturer-provided document that describes how to use the device safely and effectively. May be provided in print or electronic form.
- eIFU
- Electronic Instructions for Use — a digital IFU published on an accessible website in compliance with applicable regulations.
- Labeling
- All written, printed, or graphic matter upon or accompanying a device — includes the label on the device itself and supporting documentation.
Software-enabled devices
Software is increasingly central to medical devices. Regulatory frameworks for software have matured alongside clinical-grade AI.
- SaMD
- Software as a Medical Device — software intended to be used for medical purposes without being part of a hardware device.
- SiMD
- Software in a Medical Device — software that is embedded in or accompanies a hardware medical device.
- PCCP
- Predetermined Change Control Plan — a framework that allows manufacturers to update software-enabled devices in pre-specified ways without resubmitting for clearance.
- SBOM
- Software Bill of Materials — an inventory of software components and dependencies, increasingly required for medical device cybersecurity compliance.
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