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hairspring

[hair-spring] /ˈhɛərˌsprɪŋ/
noun, Horology
1.
a fine, usually spiral, spring used for oscillating the balance of a timepiece.
Also called balance spring.
Origin
1820-1830
1820-30; hair + spring
Dictionary.com Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2014.
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British Dictionary definitions for hair-spring

hairspring

/ˈhɛəˌsprɪŋ/
noun
1.
(horology) a very fine spiral spring in some timepieces, which, in combination with the balance wheel, controls the timekeeping
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
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7
6
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