When dealing with Windows NTFS file system permissions, one quickly encounters the SYNCHRONIZE access right, the purpose of which may not be obvious. SYNCHRONIZE belongs to the standard access rights, just like DELETE, READ_CONTROL, WRITE_DAC and WRITE_OWNER.
Here is the definition of SYNCHRONIZE from MSDN:
The SYNCHRONIZE access right is defined within the standard access rights list as the right to specify a file handle in one of the wait functions.
Source:File Security and Access Rights on MSDN