The Collaborative International Dictionary of English v.0.48:

Myalgia \My*al"gi*a\, n. [NL., fr. Gr. ? muscle + ? pain.]
   (Med.)
   Pain in the muscles; muscular rheumatism or neuralgia.
   [1913 Webster]

WordNet (r) 3.0 (2006):

myalgia
    n 1: pain in a muscle or group of muscles [syn: myalgia,
         myodynia]