IGM

noun3

1. •
   Abbreviation of InterGalactic Medium.
2. •
   Initialism of International Grandmaster
3. •
   Initialism of in-game module.

   • Blood Pitᵀᴹ — an “In-Game Module” (IGM) quest for the Adventures of Renownᵀᴹ Gaming System. — 2016

noun1

1. •
   Immunoglobulin M.