main·​spring | \ ˈmān-ˌspriŋ How to pronounce mainspring (audio) \

Definition of mainspring

1 : the chief spring in a mechanism especially of a watch or clock
2 : the chief or most powerful motive, agent, or cause

Examples of mainspring in a Sentence

Agriculture is the mainspring of their economy.

Recent Examples on the Web

In the Type 390, the movement is arranged so that the gear trains lie in layers, from right to left, with the mainspring at one end and the tourbillon at the other., "A $300,000 Watch for Your $3.26 Million Sports Car," 3 Apr. 2018 In a conventional watch gear train, gears downstream in the power flow from the mainspring barrel turn more quickly than the gears that drive them., "A $300,000 Watch for Your $3.26 Million Sports Car," 3 Apr. 2018 The show’s mainspring and title song amounts to little more than a kvetch. Lily Janiak, San Francisco Chronicle, "Not much of a ‘Saturday Night’ except for Sondheim devotees," 2 Apr. 2018 This paranoia was the mainspring for Nixon’s attack on the constitutional order. Jeet Heer, New Republic, "Trump’s Cult of Personality Takes Paranoia to the Next Level," 26 Jan. 2018 At the end of the day, the headline is going to be what Jane Fleming Kleeb, the chairman of the Nebraska Democratic Party and the mainspring of the opposition to the project, said after the hearings adjourned on Thursday afternoon. Charles P. Pierce, Esquire, "Why the Keystone Battle, and Others Like It, Will Never End," 10 Aug. 2017 The mainspring of this imagined future clash is not race and slavery, but science and the environment. The Washington Post,, "Omar El Akkad's 'American War' blends 19th-century hatreds, 21st-century weapons," 30 May 2017 To build the Reference, Patek adapted self-winding technology from its rival, Rolex: a new mechanism that spun around the mainspring instead of swinging back and forth. Jonathon Keats, WIRED, "Design: Evolution of the Self-Winding Wristwatch," 11 Nov. 2009

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'mainspring.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

See More

First Known Use of mainspring

1591, in the meaning defined at sense 1

Keep scrolling for more

Learn More about mainspring

Statistics for mainspring

Look-up Popularity

Time Traveler for mainspring

The first known use of mainspring was in 1591

See more words from the same year

Keep scrolling for more

More Definitions for mainspring



English Language Learners Definition of mainspring

: the most important spring in a watch or clock
: the most important or powerful cause or part of something


main·​spring | \ ˈmān-ˌspriŋ How to pronounce mainspring (audio) \

Kids Definition of mainspring

: the principal spring in a mechanical device (as a watch or clock)

More from Merriam-Webster on mainspring

Rhyming Dictionary: Words that rhyme with mainspring Encyclopedia article about mainspring

Comments on mainspring

What made you want to look up mainspring? Please tell us where you read or heard it (including the quote, if possible).


having a desire to acquire more things

Get Word of the Day daily email!

Test Your Vocabulary

Words for Summer: A Quiz

  • a closeup of a sunflower
  • Which of the following words means “of or relating to summer”?
How Strong Is Your Vocabulary?

Test your vocabulary with our 10-question quiz!


Test Your Knowledge - and learn some interesting things along the way.

Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!