CDL Glossary
Plain-language definitions for the terms used across this site, most of them grounded directly in 49 CFR Part 383's own definitions section.
- Air Brake Restriction
- A note on a CLP or CDL barring the holder from operating any CMV equipped with air brakes. It's applied if you fail the air brake portion of the knowledge test, or take your skills test in a vehicle that doesn't have air brakes.Source: 49 CFR 383.95
- Alcohol Concentration
- The amount of alcohol in a person's blood or breath, expressed as grams of alcohol per 100 milliliters of blood or grams of alcohol per 210 liters of breath.Source: 49 CFR 383.5See Alcohol, Other Drugs, and Driving practice questions →
- CDL (Commercial Driver's License)
- A license issued by your state or jurisdiction of domicile that authorizes you to operate a specific class of commercial motor vehicle.Source: 49 CFR 383.5See How to Get Your CDL →
- CDL Downgrade
- A change to a lower self-certification category or a loss of CDL privileges, triggered by one of a specific set of conditions defined in federal regulation, such as no longer meeting medical certification requirements.Source: 49 CFR 383.5See DOT Medical Card Requirements →
- Class A CDL
- Required for any combination of vehicles with a gross combination weight rating of 26,001 pounds or more, provided the towed vehicle weighs more than 10,000 pounds.Source: 49 CFR 383.91
- Class B CDL
- Required for any single vehicle with a gross vehicle weight rating of 26,001 pounds or more, or such a vehicle towing a unit of 10,000 pounds or less.Source: 49 CFR 383.91
- Class C CDL
- Required for a vehicle or combination that doesn't meet the Class A or B thresholds but is designed to carry 16 or more passengers including the driver, or is used to transport placarded hazardous materials.Source: 49 CFR 383.91
- CLP (Commercial Learner's Permit)
- A permit that lets you practice driving a CMV while accompanied by a valid CDL holder, before you're eligible to take the skills test. Issued after passing the knowledge test; valid for up to a year, and you must hold it at least 14 days before testing for your CDL.Source: 49 CFR 383.5, 383.25See How to Get Your CDL →
- CMV (Commercial Motor Vehicle)
- A motor vehicle or combination of vehicles used in commerce to transport passengers or property, meeting specific weight or passenger-count thresholds.Source: 49 CFR 383.5
- Combination Vehicle
- A tractor-trailer or other combination with a gross combination weight rating or actual weight of 26,001 pounds or more, the vehicle type tested by the Combination Vehicles section of the CDL exam.Source: 49 CFR 383.5
- Disqualification
- Losing the right to drive a CMV. This can mean your CLP or CDL is suspended, revoked, or canceled, some other withdrawal of your driving privilege, or FMCSA determining you're not qualified.Source: 49 CFR 383.5See Aggressive Driving and Road Rage practice questions →
- ELDT (Entry-Level Driver Training)
- Required theory and behind-the-wheel training for anyone getting a Class A or B CDL, or a Passenger, School Bus, or Hazmat endorsement, for the first time on or after February 7, 2022. Must come from a provider listed on FMCSA's Training Provider Registry.Source: 49 CFR 380.603, 380.605See How to Get Your CDL →
- Employer
- Anyone who owns or leases a CMV, or assigns employees to operate one.Source: 49 CFR 383.5
- Endorsement
- An authorization added to a CLP or CDL required to operate certain vehicle types: doubles/triples, passenger vehicles, tank vehicles, hazardous materials, or school buses.Source: 49 CFR 383.5, 383.93See Hazardous Materials Rule practice questions →
- Excepted / Non-Excepted
- Part of the four self-certification categories every CDL holder chooses from. "Non-excepted" means you're subject to the federal medical certification rule; "excepted" means your specific type of operation is carved out from it. Combined with interstate or intrastate to form the full category (e.g. non-excepted interstate).Source: 49 CFR 383.71(b)See DOT Medical Card Requirements →
- FMCSA
- The Federal Motor Carrier Safety Administration, the U.S. Department of Transportation agency that writes and enforces the commercial driver regulations tested on the CDL exam.
- GCWR (Gross Combination Weight Rating)
- The manufacturer-specified maximum loaded weight of a combination vehicle, or the sum of its units' individual ratings if the manufacturer hasn't specified a combined rating, whichever is greater.Source: 49 CFR 383.5
- GVWR (Gross Vehicle Weight Rating)
- The manufacturer-specified maximum loaded weight of a single vehicle.Source: 49 CFR 383.5
- Hazardous Materials
- Any material designated as hazardous under federal transportation law and required to be placarded, or any quantity of a listed select agent or toxin. Transporting placarded amounts requires the hazmat endorsement.Source: 49 CFR 383.5See Hazardous Materials Rule practice questions →
- Medical Examiner's Certificate (DOT Medical Card)
- The certificate issued after passing the physical qualification exam, required for "non-excepted interstate" drivers. Must be issued by an examiner listed on the National Registry of Certified Medical Examiners.Source: 49 CFR 391.43See DOT Medical Card Requirements →
- National Registry of Certified Medical Examiners
- FMCSA's official list of medical examiners qualified to perform the CDL physical exam. An exam from an examiner not on this registry doesn't produce a valid certificate.Source: 49 CFR Part 390 Subpart DSee DOT Medical Card Requirements →
- Out-of-Service Order
- A declaration by an authorized enforcement officer that a driver, vehicle, or motor carrier operation may not continue until a specific condition is corrected.Source: 49 CFR 383.5
- Placard
- A diamond-shaped warning sign required on each side and each end of a vehicle carrying a large enough quantity of a hazardous material, identifying the hazard class being transported.Source: 49 CFR 172.504See Hazardous Materials Rule practice questions →
- Self-Certification
- A declaration every CDL applicant and holder must make, choosing one of four categories (non-excepted interstate, excepted interstate, non-excepted intrastate, excepted intrastate) that determines whether you're federally required to hold a medical certificate.Source: 49 CFR 383.71(b)See DOT Medical Card Requirements →
- Serious Traffic Violation
- A specific list of violations, including reckless driving, improper lane changes, and following too closely, that trigger a CDL disqualification (60 days on a second offense within 3 years, 120 days on a third) whether committed in a CMV or a personal vehicle.Source: 49 CFR 383.51See Aggressive Driving and Road Rage practice questions →
- Skills Test
- The hands-on CDL exam, covering three parts: a pre-trip vehicle inspection, basic vehicle control, and safe on-road driving. All three must be passed.Source: 49 CFR 383.113See How to Get Your CDL →
- Tank Vehicle
- A CMV designed to transport liquid or gaseous material in a permanently mounted tank or tanks with a combined capacity of 1,000 gallons or more, the vehicle type requiring the tanker endorsement.Source: 49 CFR 383.5
- TPR (Training Provider Registry)
- FMCSA's list of entities authorized to deliver entry-level driver training. Training from a provider not on this registry doesn't satisfy the ELDT requirement.Source: 49 CFR 380.605See How to Get Your CDL →