Also found in: Acronyms, Wikipedia.
intracluster medium(in-tră-klus -ter) (ICM) The invisible medium that lies between the galaxies in a cluster. It is mostly comprised of hot (107–108 K) gas emitting strongly in X-rays. See clusters of galaxies; X-ray astronomy.
intracluster medium[‚in·trə′kləs·tər ‚mēd·ē·əm]
A hot, tenuous gas that fills the space between the members of a cluster of galaxies and emits x-rays.