Wiktionary
n. (context biology English) An endocytic vacuole through which molecules internalized during endocytosis pass en route to lysosomes
Wikipedia
In cell biology, an endosome is a membrane-bound compartment inside eukaryotic cells. It is a compartment of the endocytic membrane transport pathway originating from the trans Golgi membrane. Molecules or ligands internalized from the plasma membrane can follow this pathway all the way to lysosomes for degradation, or they can be recycled back to the plasma membrane. Molecules are also transported to endosomes from the trans- Golgi network and either continue to lysosomes or recycle back to the Golgi. Endosomes can be classified as early, sorting, or late depending on their stage post internalization. Endosomes represent a major sorting compartment of the endomembrane system in cells. In HeLa cells, endosomes are approximately 500 nm in diameter when fully mature.
Usage examples of "endosome".
You can see that a cell is just millions of objects—lysosomes, endosomes, ribosomes, ligands, peroxisomes, proteins of every size and shape—bumping into millions of other objects and performing mundane tasks: extracting energy from nutrients, assembling structures, getting rid of waste, warding off intruders, sending and receiving messages, making repairs.