Placard Meanings Dictionary
A placard meanings dictionary is simply the nine hazard classes paired with what each one means: its color, its symbol, and the danger it represents. Class 1 explosives, 2 gases, 3 flammable liquids, 4 flammable solids, 5 oxidizers, 6 poison, 7 radioactive, 8 corrosives, 9 miscellaneous. Learn the nine and you can read almost any placard.
The dictionary is the nine classes
There is no long glossary to memorize; the whole placard dictionary comes down to nine hazard classes. Each class has a color, a symbol, and a meaning, and once you know those nine entries you can interpret the vast majority of placards you will ever see.
The nine entries
This is the core dictionary:
| Class | Color | Meaning |
|---|---|---|
| 1 | Orange | Explosives |
| 2 | Red / green / white | Gases (flammable / non-flammable / toxic) |
| 3 | Red | Flammable liquids |
| 4 | Red-and-white / red / blue | Flammable solids, dangerous when wet |
| 5 | Yellow | Oxidizers and organic peroxides |
| 6 | White | Poison and infectious substances |
| 7 | Yellow over white | Radioactive |
| 8 | White over black | Corrosives |
| 9 | White with black stripes | Miscellaneous |
The nine-class dictionary. Confirm specifics and divisions in your official CDL manual.
How to use the dictionary
Read any placard in the same order every time: color first to find the family, then the symbol to confirm the type, then the class number to pin it down. That three-step decode turns the dictionary into a fast lookup you can run in a second, rather than a list to recite.
The divisions behind the entries
A few classes split into divisions with their own looks, which expands the dictionary slightly. Class 2 has flammable (red), non-flammable (green), and toxic (white) gases. Class 1 has six explosives divisions. Classes 4, 5, and 6 also split. You still start from the nine main entries and add the divisions as you go.
How to study and verify
Treat the nine classes as the master list, learn each by color and symbol, then drill the look-alikes (Class 8 versus 9, poison versus toxic gas, the Class 2 gases). That covers the dictionary in a usable way. For the exact definitions and any edge cases, your official state CDL manual is the authority.
Frequently asked questions
- What do the hazmat placards mean?
- Each of the nine hazard classes has a meaning: 1 explosives, 2 gases, 3 flammable liquids, 4 flammable solids, 5 oxidizers, 6 poison, 7 radioactive, 8 corrosives, 9 miscellaneous, shown by color and symbol. Confirm in your official manual.
- How many placard classes are there?
- Nine hazard classes, several of which split into divisions (like the three Class 2 gas divisions). Learning the nine plus the common divisions covers almost any placard.
- What is the fastest way to read a placard?
- Color first to find the hazard family, then the symbol to confirm the type, then the class number to pin it down. That order decodes any diamond quickly.