1) A small, membrane-bounded organelle that uses molecular oxygen to oxidize organic molecules; contains some enzymes that produce and others that degrade hydrogen peroxide.

2) Microbodies which occur in animal and plant cells and in certain fungi and protozoa. They contain peroxidase, catalase, and allied enzymes.

3) A cytoplasmic cell organelle containing enzymes (as catalase) which act especially in the production and decomposition of hydrogen peroxide -- called also microbody.