Which is the correct term haploid daughter cells or haploid parent cells? Meiosis 2 begins with 2 haploid parent cells and ends with 4 haploid daughter cells (gametes). Gametes from the opposite sex can now merge together and fertilize. If I were to refer to a specific haploid daughter cell merging with another to produce a **zygote** ; are these daughter cells from Meiosis 2 still called 'daughter' cells or are they now called parent cells?

"Parent" and "daughter" terminology is indeed relative. Any parent cell has been a daughter at some point. However, in the case of the zygote there is no "parent" strictly speaking since it is the result of a fusion between two cells, that you may call "daughter cells" only if you are referring to the previous meiosis event.

In this particular case, there is no cell division, so no "daughter" is formed, so no point in calling the haploid cells from M2 "parents" either.