The outermost cell envelope of GRAM-NEGATIVE BACTERIA composed of PHOSPHOLIPIDS; LIPOPOLYSACCHARIDES (LPS), and BACTERIAL OUTER MEMBRANE PROTEINS. The bacterial outer membrane LPS demonstrates cytotoxicity (see LIPID A and BACTERIAL O ANTIGEN).

Synonyms: Membrane, Bacterial Outer, Outer Membrane, Bacterial, Bacterial Outer Membrane, Bacterial Outer Membranes