Is there a mathematical term to refer to the number of unique elements in a multiset/sequence/tuple?

Question

Does there exist a mathematical term to refer to the number of unique elements in a multiset/sequence/tuple? For example, if a tuple $T$ is $[2, 4, 2, 10, 4, 8, 10]$, then the number of unique elements in $T$ is $4$: $$[2, 4, 8, 10].$$ The term “cardinality” is not suitable because, according to Wikipedia, if $M = \{a, a, b, b, b, c\}$ is a multiset, then its cardinality is $6$, although the number of unique elements in $M$ is $3$:$$\{a, b, c\}.$$

Answer 1

I have found that the term “dimension” may be suitable here (source):

The root set (or support set) of a multiset is the set of its distinct elements. The dimension of a multiset is the cardinality of the support set.