Proto-Indo-European root meaning "to do."
It forms all or part of: allergic; allergy; argon; boulevard; bulwark; cholinergic; demiurge; dramaturge; energy; erg (n.1) "unit of energy;" ergative; ergonomics; ergophobia; George; georgic; handiwork; irk; lethargic; lethargy; liturgy; metallurgy; organ; organelle; organic; organism; organize; orgy; surgeon; surgery; synergism; synergy; thaumaturge; work; wright; wrought; zymurgy.
It is the hypothetical source of/evidence for its existence is provided by: Greek ergon "work," orgia "religious performances;" Armenian gorc "work;" Avestan vareza "work, activity;" Gothic waurkjan, Old English wyrcan "to work," Old English weorc "deed, action, something done;" Old Norse yrka "work, take effect."
"organism of several forms; an individual organism which differs from others of the same group or species," 1828, from Greek polymorphos "of many forms" (see polymorphous). Related: Polymorphic (1816).
also pathogene, "disease-producing micro-organism," 1880, a back-formation from pathogenic.
also auto-immune, "arising from an abnormal immune response to a normal body part," 1952, from auto- + immune. Related: Autoimmunity, attested by 1903 as "immunity, natural or acquired, effected by the unaided powers of the organism, independent of external agencies." The modern sense of "immune responses of an organism against its own healthy cells and tissues" is from 1950s.
"animal form containing all elements of a typical organism of its group," 1864, from Greek zōon "animal," from PIE root *gwei- "to live."