Collective name for the X- and Z-chromosomes
I think you can safely use the terms heterogametic (Y/W) and homogametic (X/Z) chromosomes, meaning that a heterogametic chromosome is the chromosome which makes one of the sexes heterogametic (i.e. defines the difference between the two types of gametes of the respective sex).

These terms applied to chomosomes do have some usage in the literature, e.g. in this article.