The word fascicle derives from the Latinfascis ("bundle").
Fascicles are the sections of a book, usually a reference work, that because of its length, is issued in parts so that the information may be made available to the public as soon as possible rather than waiting years or decades to complete the entire work. The Oxford English Dictionary was published in fascicles over many years, as was the Dictionary of American English. Volume 4 of Donald Knuth's The Art of Computer Programming is currently being published in this form.
"Fascicle" often refers to the booklets in which Emily Dickinson inscribed many of her poems.