1) the artificial process of removing waste products from the blood, e.g. when the kidneys are not working (dialysis)

2) a mass of cells and cell products in an animal body; (a piece of) thin, soft paper for wrapping things etc; a series (tissue)

3) (of) a person who eats no meat or any produce form animal such as milk, eggs (and who does not wear or use animal products such as leather) (vegan)