The term 'Apple Pie Pros' refers to a group of people who are experts in making apple pies. The four letter word MOMS is an acronym for this group, which stands for 'Masters of Making Apple Pies'. This group of professionals is highly skilled in the art of baking apple pies and can create delicious pies with perfect crusts and fillings. They are often sought after by restaurants and bakeries for their expertise in creating the perfect apple pie.