Definition

Noun: 1. The principal spring in a mechanical device: The most important spring, especially in a clock or watch, which provides the primary motive force as it unwinds. 2. The chief motivating force or reason: (Figurative) The primary driving factor or central cause behind an action, event, or situation.

Usage and Examples

• The watchmaker carefully replaced the broken mainspring to restore the timepiece's function.
• In the novel, the character's quest for revenge is the mainspring of the entire plot.
• Curiosity is often the mainspring of scientific discovery.

Advanced Usage

• "To be the mainspring of something": To be the central, driving force behind something.
  • Her unwavering optimism was the mainspring of the team's resilience during the difficult project.

Variants and Related Words

• Mainspring barrel (n): The cylindrical casing that holds the mainspring in a timepiece.
• Mainspring winder (n): A specialized tool used by watchmakers to install a mainspring into its barrel.

Synonyms

• (For the mechanical sense): Drive spring, motor spring.
• (For the figurative sense): Driving force, prime mover, impetus, motivation, catalyst.

Idioms and Phrases

• The mainspring of one's actions: The fundamental reason why someone behaves in a certain way.
  • A deep-seated fear of failure was the mainspring of his actions.

Noun

1. the most important spring in a mechanical device (especially a clock or watch); as it uncoils it drives the mechanism