Helicopter
late 19th century: from French hélicoptère, from Greek helix ‘spiral’ + pteron ‘wing’.
wiktionary
Borrowed from French hélicoptère, from Ancient Greek ἕλιξ(hélix, “spiral”) + πτερόν(pterón, “wing”). Doublet of helicopteron.
etymonline
helicopter (n.)
1861, from French hélicoptère "device for enabling airplanes to rise perpendicularly," thus "flying machine propelled by screws." From a Latinized combining form of Greek helix (genitive helikos) "spiral" (see helix) + pteron "wing" (from PIE root *pet- "to rush, to fly").
The idea was to gain lift from spiral aerofoils, and it didn't work. Used by Jules Verne and the Wright Brothers, the word was transferred to helicopters in the modern sense by 1918 when those began to be developed. Nativized in Flemish as wentelwiek "with rotary vanes."
