Quick definition:Filler is anime content that does not appear in the original manga, usually episodes or story arcs added to give the manga time to build up more chapters.
Meaning
Filler refers to episodes or whole arcs of an anime that are not based on the source material, which is usually a manga. They are written by the anime staff, often to avoid running out of story. When a series catches up with the manga, the studio may add original episodes and story arcs, sometimes called filler arcs, while the author draws more chapters.
Filler can be disappointing for viewers who want the main plot, which is why many fans use lists to see which episodes to skip. Not all filler is poor, however. Some original episodes expand the characters or show everyday life, and a few are widely loved. Fans may also use the word for any episode that does not move the main story forward.
Series that follow the manga closely are said to be faithful, and recap episodes, which summarise earlier events, are sometimes counted as filler too.
Origin:Filler is an English word meaning something used to fill a gap, and television viewers have long used it for content that fills time. In anime fandom it came to mean original material added between the canonical story, particularly when a series catches up with its manga. There is no known single origin for this usage.
Example:A long-running adventure series reaches the end of the manga's available chapters, but the show still needs weekly episodes, so the writers invent a new storyline, such as a side trip to an unfamiliar island with new characters. Viewers following the main plot might skip these episodes and rejoin when the series returns to the manga.
Did you know?Fullmetal Alchemist was first adapted with its own original storyline, then remade as Brotherhood to follow the manga's story more closely. This is a well-known case of a studio replacing the first adaptation's added content.