Filler is material added to something to take up space, extend its length, or make it seem more substantial than it really is. When a teacher assigns a five-page essay and a student runs out of ideas after three pages, those extra paragraphs that don't really say anything new are filler.

You'll encounter filler in many contexts. Some foods contain filler ingredients, like breadcrumbs mixed into meatloaf to stretch the meat further. In conversation, people use filler words like “um,” “like,” and “you know” while thinking of what to say next. Television shows sometimes include filler episodes that don't advance the main story, just taking up time between important plot developments.

The word carries a slightly negative connotation because filler rarely adds real value. It's the difference between a book with 300 pages of gripping story and one with 200 pages of story plus 100 pages of unnecessary description just to make it longer. When something is described as just filler, it means you could remove it without losing anything important.