Definition of mu-sickness in English:

mu-sickness

(also moor-sickness, møa-sickness, mua-sickness)

noun

Shetland, Scottish
  • A wasting disease of sheep; specifically liver rot (hepatic fascioliasis) and cobalt deficiency.

Origin

Early 19th century. From Shetland Scots mu, mø, in the same sense (from the unattested Norn reflexes of the early Scandinavian words represented respectively by Old Icelandic móðr and moeði) + sickness; compare Norwegian modsott, Danish modsot sickness characterized by a feeling of exhaustion.

Pronunciation

mu-sickness

/ˈmuːsɪknəs/