Fitting can refer to: Any machine, piping or tubing part that can attach or connect two or more larger parts. For examples, see coupling, compression fitting or piping and plumbing fittings. The process of applying regression analysis to data. This method is sometimes called line-fitting or curve fitting depending on the end result. Preprocessing of data for data mining or other parsing. Mathematical concepts named after Hans Fitting such as Fitting subgroup, Fitting length, Fitting lemma, and Fitting's theorem. Light socket or lamp fitting.