lysosome ly·so·some (lī'sə-sōm')
A membrane-bound organelle in the cytoplasm of most cells containing various hydrolytic enzymes that function in intracellular digestion.
A cell organelle that is surrounded by a membrane, has an acidic interior, and contains hydrolytic enzymes that break down food molecules, especially proteins and other complex molecules. Lysosomes fuse with vacuoles to digest their contents. The digested material is then transported across the organelle's membrane for use in or transport out of the cell. See more at cell.