What does MOM stand for? What does ADT stand for?
MOM stands for "message oriented middleware." This is a type of middleware in which distributed processes interact in a losely-coupled fashion, by exchanging self-describing "messages." A message is a data structure with a header and a body. That data structure can be read and written through an API (application programming interface).
On meaning of the acronym ADT is "abstract datatype," but there might be other usages of the acronym. I would need some context information to find out.