Definition
A specific section of U.S. federal law (Title 49, Part 171, Section 171.8) that contains the official definitions used throughout the hazardous materials transportation regulations, including those that apply to material carried by aircraft.
Plain English
It is the part of the federal rulebook that lists what the words mean when the government talks about shipping dangerous goods, including by air.
Context Anchor
Seen in FAA and AIM glossary material when a hazardous-materials term is being tied to its official legal definition.
Derivation
The Code of Federal Regulations (CFR) is the published collection of all current federal rules. Title 49 covers Transportation. Part 171 covers general information and definitions for hazardous materials. Section 171.8 is the specific subsection where those definitions are written down. The number works like an address: Title.Part.Section.
Why Pilots Care
Pilots must know whether cargo or equipment on board meets the definitions in this section so they can apply proper packaging, labeling, documentation, and emergency procedures required by law.
Analogy
It is like a street address for a rule: 49 tells you the larger rulebook, 171 tells you the part, and .8 tells you the exact section to read.
Intuition Check
Do not read “code” here as a secret code or a radio code. Here it means an organized federal rulebook, and “171.8” is the exact section number inside it.
Example Sentence 1
The hazmat training manual cited 49 CFR 171.8 for the formal definition of 'hazardous material.'
Example Sentence 2
Under the definitions in 49 CFR 171.8, certain lithium batteries are regulated for air transport.