Depends on the properties and behavior of the material. Liquefaction is a term for soil/dirt.sand briefly behaving like a liquid during earthquakes or when air is pumped through it from the bottom. Non-newtonian liquid is a term for: “fluid whose viscosity is variable based on applied stress or force”. You also have materials like glass that appear to be solid but actually behave like liquids over long enough time scales, also known as amorphous solids.
Not really answering your question but its the best i can do 
Something-something harmonic frequency? I dunno.
