The word "spool" in the context of printer output is derived from the acronym "Simultaneous Peripheral Operations On-Line." In early computer systems, when a user sent a print job to a printer, the data was typically stored on a magnetic tape or disk before being printed. This allowed the computer to continue processing other tasks while the printer worked on the print job.

To facilitate this process, the data was initially stored in a temporary storage area called a "spool." The term "spool" was used to describe the process of buffering the print job and making it available to the printer in a sequential manner.

Over time, the term "spool" became more commonly used to refer to the process itself, as well as the temporary storage area. Today, "spooling" generally refers to the practice of storing data in a queue or buffer before it is processed by a device or system, not just limited to printers.