Source : Webster's Revised Unabridged Dictionary (1913)

Red-gum \Red"-gum`\ (-g?m`), n. [OE. reed gounde; AS. re['a]d
   red + gund matter, pus.]
   1. (Med.) An eruption of red pimples upon the face, neck, and
      arms, in early infancy; tooth rash; strophulus. --Good.

   2. A name of rust on grain. See {Rust}.