When you thicken a liquid or when it thickens, it becomes stiffer and more solid. Thicken the broth with the cornflour Keep stirring until the sauce thickens
People sometimes say `the plot thickens' when a situation or series of events is getting more and more complicated and mysterious. `Find anything?' he asked. `Yeah. The plot thickens,' I said. to become thick, or make something thick
become thick or thicker; "The sauce thickened"; "The egg yolk will inspissate" make thick or thicker; "Thicken the sauce"; "inspissate the tar so that it becomes pitch" make viscous or dense; "thicken the sauce by adding flour