per·oxi·some \pəˈräksə̇ˌsōm\noun (-s) Etymology:peroxide + -some (III) : a cytoplasmic cell organelle that contains catalytic enzymes (as catalase) which act in oxidative reactions and especially in the production and decomposition of hydrogen peroxide • per·oxi·som·al\-ˌräksə̇¦sōməl \adjective