v. t. 1. To clean the oil from (wool) after combing. Ash. [ 1913 Webster ]
2. (Chem.) To clean (a filter, a chromatography column, a water softener, etc.) by passing liquid through in the reverse of the normal direction of flow. This procedure dislodges particles which clog the pores of the filter or column packing, removing them from the filter or column. [ PJC ]