The term in vitro is associated with various biological processes that are made to occur outside the living organism. Etymologically, it is a Latin for within a glassware (i.e. in- pertains to within and vitreus, glassware). The term in vitro is typically written in italics.
An example of its usage is in vitro study. An in vitro study is a type of study wherein the methodology involves a biological process made to occur outside the living organism at the laboratory for experimentation and observation. For instance, a protein's biological process made to occur in a laboratory for observation and experimentation implicates a study conducted in vitro.
The term in vitro is used in contrast to the term in vivo. The latter pertains to a biological process made to occur inside the normal biological context.