Parenchyma (ə/) is the bulk of a substance. In animals, a parenchyma comprises the functional parts of an organ and in plants parenchyma is the ground tissue of nonwoody structures.
The term "parenchyma" is New Latin from Greek παρέγχυμα parenkhyma, "visceral flesh" from παρεγχεῖν parenkhein, "to pour in" from παρα- para-, "beside", ἐν en-, "in" and χεῖν khein, "to pour".
Originally, Erasistratus and other anatomists used it to refer to certain human tissues. Later, it was also applied to some plant tissues by Nehemiah Grew.