an adjustment that causes something to occur or recur in unison
a process that compares the content on your mobile phone with the content on your PC and updates each to contain the latest, most up to date information (eg calendar appointments, phonebook entries, etc). It has nothing to do with swimming.
A process that causes something to occur or recur at the same time or in unison. Synchronisation can be used to make the contents of specific files identical on different devices. For example, a user can synchronise the phonebook or contacts, calendar, and to-do list of a mobile device with the corresponding PC applications. This is not possible with all mobile phone models.