Emily Dickinson Lexicon

FULL, v.t. [Sax. fullian; L. fullo; D. vollen, vullen; Fr. fouler; to tread, to press, to full; foule, a crowd; It. folla, and folta, a crowd; folto, dense; allied to Eng. felt, filter, It. feltro, from being thick or fulled. Sax. feala, many, Gr. πολλοι, that is, a crowd, a throng. Foul and defile are probably of the same family. As the French fouler signifies to tread and to full cloth, so walker, a fuller, is from the root of walk.]

To thicken cloth in a mill. This is the primary sense; but in practice, to full is to mill; to make compact; or to scour, cleanse and thicken in a mill.