Set within a partition

Question

Say I have a partition of the set $\{1,2,3,4,5\}$. The partition is $\{\{1,3\},\{2\},\{4\},\{5\}\}$

Is there a word for set within a partition e.g. I want to say, 'one of the sets of the partition always have cardinality two' i.e. $\{1,3\}$

Is is correct to say 'set of the partition' referring to the set $\{1,3\}$.

Thanks

Answer 1

From Wikipedia:

The sets in P are called the blocks, parts or cells of the partition.

Regarding your question, though, I'd rather call $\{1,3\}$ a 'set in the partition' or 'element of the partition' than a 'set of the partition,' but that's just a personal preference.