Originally designed in 1966 and constantly updated over the years, MUMPS derives its name from Massachusetts General Hospital Utility Multi-Programming System) or alternatively M. As you should gather from the name the original need was driven by large hospitals (and ultimately banks) to drive high-throughput multi-user transaction processing. As RDBMS emerged (and ultimately NoSQL and NewSQL) MUMPS remained not only viable but superior in performance and capabilities that includes even today.
The original problem to be solved was how to receive, store, and process the wide array of tests and other variables being rapidly generated and collected on a single ICU patient in just one day. That would include at least 12 different variables including temperature, heart rate, blood oxy, blood pH, and others. The data generated via sensors (electrodes) measure many factors in real time, plus lab tests done multiple times per day per patient. On average the data needs to be accessed by about 20 doctors and medical staff for each patient and there are hundreds of thousands of patients.
The thing that particularly strikes me is how this resembles streaming data problems of IoT that we are only recently solving with Spark and Storm, but were solved perfectly adequately 40 and 50 years ago by MUMPS. MUMPS by Any Other Name.
The original copyrights on MUMPS expired about a decade ago. An improved successor version is actively marketed by InterSystems Corp. under the name Caché. A version known as GT.M is available for Linux under a Free Open Source license. Googling either of these names will be as efficient as looking under MUMPS. There was also a movement some years back to simply call it “M” and you will sometimes see it identified as MUMPS/M.