mainspring

Etymology
From. For figurative sense, compare.

Noun

 * 1)  The principal spring of a clockwork mechanism, which drives it by uncoiling.
 * 2)  The most important reason for, or element of, something.
 * 1)  The most important reason for, or element of, something.

Translations

 * Armenian:
 * Catalan: ressort motor
 * Chinese:
 * Egyptian Arabic: زمبلك
 * Estonian:
 * Finnish:
 * French: ressort moteur
 * German: Antriebsfeder,, Hauptfeder
 * Ido: granda resorto
 * Japanese: ぜんまいばね
 * Kannada:
 * Kurdish:
 * Northern Kurdish: zenbelka serekî
 * Manx: ard-lheimaghan
 * Polish: sprężyna napędowa
 * Spanish: resorte motor
 * Tamil:
 * Thai:
 * Turkish:
 * Urdu: بڑی کمانی
 * Vietnamese: dây cót chính