ME/CFS
From MEpedia, a crowd-sourced encyclopedia of ME and CFS science and history
The acronym ME/CFS is commonly used as an umbrella term to cover the various case definitions employed to describe Myalgic Encephalomyelitis (ME) and/or Chronic Fatigue Syndrome (CFS) around the world. Case definitions vary widely, with some being so broad as to cover numerous unrelated illnesses.[1] Even among the narrower case definitions, it is unclear if (ME) is equivalent to (CFS), a specific form of it, or something entirely different. In ME/CFS research, the terms are often used synonymously, though there is no clear evidence to support either equating them or separating them.
In the UK and parts of Europe, the acronym is CFS/ME.