"I should like to suggest the noun hemizeuxis (a half yoking) and the corresponding adjective hemizygous (half yoked). Should such a suggestion prove acceptable there would be the three adjective series: homozygous, heterozygous, and hemizygous, referring to the three possible conditions with respect to any single gene, namely, ‘like mates’, ‘differing mates’, and ‘no mate’" (OED).