A (proper) vertex coloring of a graph is a labelling of the graph’s vertices with colors such that no two vertices sharing the same edge have the same color. A coloring using at most $k$ colors is called a (proper) $k$-coloring.
The $k$-coloring partitions the vertex set of a graph into $k$ sets. What do I say to refer to one of these sets of vertices? For example, "fix a vertex coloring of $G$ and let $A$ be the (blank) of largest order."
Is there a standard terminology? Also, if there are multiple terms, what other words for these might I see floating around?