The Collaborative International Dictionary of English v.0.48:

Myeloplax \My*el"o*plax\, n.; pl. E. Myeloplaxes, L.
   Myeloplaces. [NL., fr. Gr. myelo`s marrow + ? anything flat
   and broad.] (Anat.)
   One of the huge multinucleated cells found in the marrow of
   bone and occasionally in other parts; a giant cell. See
   Osteoclast.
   [1913 Webster]