Rheology
Rheology (; from Ancient Greek ῥέω (rhéō) 'flow' and -λoγία (-logía) 'study of') is the study of the flow of matter, primarily in a fluid (liquid or gas) state, as well as "soft solids", which experience conditions under which they respond with plastic flow rather than elastic deformation to forces applied to them. Rheology is the branch of physics that deals with the deformation and flow of materials, both solids and liquids.