"substance forming the essential stuff of the cells of plants and animals," 1848, from German Protoplasma (1846), used by German botanist Hugo von Mohl (1805-1872), on notion of "first-formed," from Greek prōtos "first" (see proto-) + plasma "something formed or molded" (see plasma).
The word was in Medieval Latin with a sense of "first created thing," and it might have existed in ecclesiastical Greek in a different sense. It was used 1839 by Czech physiologist Johannes Evangelista Purkinje (1787-1869) to denote the gelatinous fluid found in living tissue. The modern meaning is a refinement of this. This word prevailed, though German language purists preferred Urschleim. Related: Protoplasmal; protoplasmic.