parenchyma (n.)

"the proper tissue or substance of any organ or part," as distinguished from connective tissue, etc., 1650s, Modern Latin, from Greek parenkhyma "something poured in beside," from para- "beside" (see para- (1)) + enkhyma "infusion," from en- "in" + khein "to pour" (from PIE root *gheu- "to pour"). In ancient physiology, the stuff that was supposed to make up the liver, lungs, etc., which was believed to be formed from blood strained through the capillaries and congealed. Related: Parenchymal; parenchymous.