spool

Etymology 1

From Middle English spole (possibly via Old Northern French spole, espole), from Middle Dutch spoele, from Old Dutch *spōla, *spuola, from Proto-Germanic *spōlǭ (“spool”), from Proto-Indo-European *spel- (“to cleave, split”). Cognate with Saterland Frisian Spoule (“spool”), Dutch spoel (“spool”), German Spule (“spool”), Swedish spole (“spool”), Icelandic spóla (“spool; reel”). The aviation usage is based on the visual similarity of one of the spools of a turbine engine to a spool used for thread (especially in cross-section).

noun

1. A reel; a device around which thread, wire or cable is wound, especially a cylinder or spindle.
   If you need to reload film, the cassette can be rewound slightly by turning the hub located on one end of its spool. 2011, Rebekah Modrak, Bill Anthes, Reframing Photography: Theory and Practice
2. (aviation) One of the rotating assemblies of a gas turbine engine, composed of one or more turbine stages, a shaft, and one or more compressor or fan stages.
   The high-pressure spool rotates faster than the intermediate- and low-pressure spools, as the high-pressure turbine is driven by superheated combustion gases straight out of the burners, while the high-pressure compressor has to spin very fast to compress air that has already been compressed and heated by the low- and intermediate-pressure compressors.
3. (computing) A temporary storage area for electronic mail, etc.

verb

1. To wind on a spool or spools.
2. (computing) To send files to a device or a program (a spooler or a daemon that puts them in a queue for processing at a later time).

Etymology 2

From blend of spa + pool.

noun

1. A small swimming pool that can be used also as a spa.