Dictionary.com
definitions

asynchronism

or a·syn·chro·ny

[ey-sing-kruh-niz-uh m]
noun
  1. a lack of synchronism or coincidence in time.

Origin of asynchronism

First recorded in 1870–75; a-6 + synchronism
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
British Dictionary definitions for asynchrony

asynchronism

noun
  1. a lack of synchronism; occurrence at different times
Derived Formsasynchronous, adjectiveasynchronously, adverb
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