CEMP stars have [C/Fe] > +1, which means compared to the Sun these stars have carbon enhanced at least ten times more than iron, and [Fe/H] < -1, meaning that iron is less than a tenth that in the Sun.
These are further categorized by whether r-process or s-process elements are enhanced.
CEMP-no stars have no enhancement.
[1] About 20% of CEMP stars fall into this category.
This article about stellar astronomy is a stub.