[fill.er] n (15c): one that fills: as a: a substance added to a product (as to increase bulk, weight, viscosity, opacity, or strength) b: a composition used to fill the pores and grain esp. of a wood surface before painting or varnishing c: a piece used to cover or fill in a space between two parts of a structure d: tobacco used to form the core of a cigar e: material used to fill extra space in a column or page of a newspaper or magazine f: a pack of paper for a loose-leaf notebook g: a sound, word, or phrase (as "you know?") used to fill pauses in speaking
[2]fil.ler n, pl fillers or filler [Hung filler] (1904): a monetary unit of Hungary equal to 1/100 forint