Pear-Apples?

Pear-Apples?

(Image from Wikipedia)

When I was five years old and staying with my maternal grandparents in their old Ozark home, my grandfather brought some pears from town and gave one to me. I ate it and told him that it was a very good apple. My grandfather -- whose family name "Perryman" implies that he would surely know -- corrected me:

"It's a pear."

Yet . . . it was once said that Adam, in his native innocence, saw into the essence of things and therefore correctly named all of the animals. Milton has the still innocent Eve name the plants (PL 11.277). In my childlike 'innocence', I knew that I was right, but I compromised and called the fruit a "pear-apple," and for the next several months whenever my grandfather went to town, I badgered him to get some more "pear-apples."

From some recent etymological work, I see that mine was not the first instance of compromise. In checking the Promptorium Parvulorum, a dictionary made in 1440 for speakers of Middle English to help them find the Latin terms for Middle English words (or so I assume, for the entries are given in Middle English), I found the following entry:

peere appul: pirumpomum, piri-pomi, neut. 2.

This entry "peere appul" is obviously the Middle English expression "pear apple" -- and the Latin "pirumpomum" just as obviously means the same thing.

What I don't know is how this expression originated. Was this a Middle English term translated back into Latin, or a Latin term translated into Middle English? If anyone knows, please comment.

By the way, here in Korea, we find the Pyrus pyrifolia, a pear that looks very much like an apple, so much so that it also bears the common name "apple pear":

Apple Pear

(Image from Wikipedia)

It also has other names, such as the apparently better-known "nashi pear." I say "apparently" because I'd never heard these called nashi pears, so I'm assuming that "nashi pear" is the British expression, for Wikipedia informs me that in India, this pear is called "nashipati."

But that presumably has nothing to do with the Middle English "peere appul" or the Latin "pirumpomum."