noun
Rare technical term; the common word is スクリュー (sense 2). Used mainly in engineering or historical contexts.
See also: スクリュー
この船は螺旋推進器で動いている。
This ship is driven by a screw propeller.
スクリュー is the common modern term for a screw propeller; 螺旋推進器 is a rare, more formal or technical synonym.
Compound of 螺旋 (spiral, helix) and 推進器 (propulsion device). The exact historical derivation is uncertain, but the term is a direct calque of the English 'screw propeller'.