1650s, Modern Latin, from Greek parenkhyma "something poured in beside," from para- "beside" (see para-(1)) + enkhyma "infusion," from en- "in" + khein "to pour" (see found, v.2). 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.