MUMPS is an acronym for Massachusettes General Hospital Utility Multi-Programming System. First developed in 1967, MUMPS is a database management system and programming language designed to process character based data. The data is stored in sparse hierarchical arrays called Globals.
The programming language, commonly referred to as M (or Open M), encourages very compact code. Each of the basic commands can be written as a single letter and intrinsic functions are called with a dollar sign followed by one or two letters. It is also fussy about spaces,sometimes one is need sometimes two. So if I wanted to print the contents of a simple Global (which are prefixed with a carat ^) called TEST the code would look something like this:
F  S A=$O(^TEST(A)) Q:A=""  D  ;
.S X=^TEST(A)
.W X,!
Debugging this stuff is laugh a minute. MUMPS mainly exists in legacy systems but there is a new product from InterSystems called Cache which is a web ready object oriented system based on MUMPS.