Thixotropic
Of fluids and gels, having the property of viscosity that decreases when stressed (by stirring or shaking) and returning to the semi-solid state upon standing.
Hence thixotropic paints, which are essentially non-drip because they return to the more solid state quickly following the cessation of stress stirring, brushing).
Some clays are thixotropic, which is important in structural and geotechnical engineering. Landslides, such as those common in the cliffs around Lyme Regis, Dorset and in the Aberfan spoil tip disaster in Wales are evidence of this phenomenon.
Some thixotropic fluids, for example ketchup, return to a gel state almost instantly while others such as yoghurt take much longer.
The word is derived from the Greek thixis, touch + -tropy. The OED gives the first usage in 1927.