sync

or synch

[singk]Informal.
noun (used esp. in the phrases in sync and out of sync)
  1. synchronization: The picture and the soundtrack were out of sync.
  2. harmony or harmonious relationship: Management wants to be in sync with the client's wishes.
verb (used with or without object)
  1. to synchronize; harmonize.

Origin of sync

First recorded in 1930–35; shortened form
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

British Dictionary definitions for synching

sync

synch

films television computing
verb
  1. an informal word for synchronize
noun
  1. an informal word for synchronizationin sync; out of sync See synchronization
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

Word Origin and History for synching

sync

1929, shortened form of synchronization (see synchronize). Originally in reference to soundtracks and pictures in the movies. Sense of "be in agreement, coincide" first recorded 1961 in in sync.

Online Etymology Dictionary, © 2010 Douglas Harper