1. a large, multinucleated giant cell associated with the resorption of bone; the nuclei resemble the nuclei of the osteoblasts and osteocytes; the cytoplasm is often foamy, and the cell frequently has branching processes. Osteoclasts may arise from stromal cells of the bone marrow. They may represent fused osteoblasts or may include fused osteocytes liberated from resorbing bone. They are usually found in close relationship to the resorption of bone and frequently lie in grooves (Howship's lacunae). 2. a large, multinucleated cell associated with the resorption of bone. Seen in irregular concavities within marginal areas of bone undergoing resorption.