spool

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 *(s)pel- (“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). See also spill.

From blend of spa +‎ pool.