1Cell Biology. Designating intracellular membranous structures consisting of a number of vesicles; specifically (especially in "multivesicular body") designating a type of endosome or lysosome consisting of a group of small vesicles contained within a limiting membrane.

2Biology and Medicine. Containing many vesicles or cavities.

3Physiology. Designating or relating to the release of a neurotransmitter from more than one synaptic vesicle.