fusee

fu·see | \ fyü-ˈzē

Definition of fusee

1 : a conical spirally grooved pulley in a timepiece from which a cord or chain unwinds onto a cylinder containing the mainspring and which by its increasing diameter compensates for the lessening power of the spring

2 : a red signal flare used especially for protecting stalled trains and trucks

History and Etymology for fusee

borrowed from French fusée "mass of thread around a spindle, explosive fuse, rocket, fusee in a timepiece," going back to Old French fusee "mass of thread around a spindle," from fus "spindle" (going back to Latin fūsus, of obscure origin) + -ee, suffix of association or containment, going back to Late Latin -āta (going back to Latin, feminine of -ātus -ate entry 3)

Note: In the later Middle Ages, French fusée designated a kind of rudimentary gunpowder-filled projectile, apparently resembling thread wound around a spindle—hence the later application to fuses, fireworks, etc.

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