Definition - What does CAS Number mean?
A CAS Number is a numerical designation for chemicals that is maintained by the Chemical Abstracts Service (CAS) of the American Chemical Society. Each number assigned by the CAS is unique to one chemical substance. There is no correlation to that scientific chemical number for the substance. CAS numbers are utilized in a range of databases to make it faster to retrieve the pertinent information about that particular chemical.
Safeopedia explains CAS Number
Chemical Abstracts Services (CAS) numbers can be up to 10 digits long and three hyphenated parts to them. The last digits are check numbers to confirm the uniqueness of the CAS number. Assignment of CAS numbers is done in sequential order as the number is entered into the database. Compounds that may be entered into the database includes such things as metals, alloys, isotopes, minerals, and inorganic compounds.