Outside the living body and/or in an artificial environment.

In a test tube.

in an artificial environment. For example many cancer research experiments are in vitro (in the test tube), using cell cultures (cells grown in the lab); either from established cell lines or from material collected at biopsy/surgery. See also: In-Vivo

'In-glass', referring to use of a cell line, microorganisms or biochemically active fraction derived from an organism (e.g. hepatocytes) in laboratory studies of biological activity, or metabolism or toxicity.

Observable in the laboratory.

Latin meaning - in glass.