What is the correct nomenclature for expressing a genotype where a recombination event may occur?
I would suggest &quot;genotype&quot;.
A Punnett square is a visualization technique to help us think, it doesn't change the terminology.
If what you mean is the 1N genotypes represented in the rows/columns that combine to make the 2N genotypes, you might consider &quot;haplotype&quot; (haploid genotype). The haploid cells with those genotypes might be called gametes, but that refers to the cell and not to the genotype.
If you are specifically interested in those genotypes/haplotypes in which a recombination event has occurred (or not), you could call them recombinants or non-recombinants. In some cases you can encounter specialized terminology, for example in yeast tetrad analysis you encounter terms such as &quot;tetratype&quot;, &quot;nonparental ditype&quot;, &quot;parental ditype&quot;. But those are not generally used outside the yeast field, I believe.