A cell has a centre called the nucleus. Cytoplasm is all the rest of the material inside the cell — the soft, jelly-like stuff and the tiny parts floating in it. It is not empty space; a lot of the cell’s daily work happens there, like moving food and building what the cell needs. You will see this word in science class and in textbooks. Everyday English almost never uses it. People sometimes wave a hand at “the inside of the cell” and say cytoplasm; strictly, that inside still has a nucleus sitting in the middle, and the cytoplasm is everything except that nucleus.

細胞質