The phase of a culture of microorganisms or animal and plant cells cultured
in vitro that follows the exponential growth phase and in which there is little or no growth.
In some cases it is a phase of product formation, e.g. formation of
secondary metabolites.
Source:
PAC, 1992, 64, 143
(Glossary for chemists of terms used in biotechnology (IUPAC Recommendations 1992))
on page 166