Samsung SyncMaster 225MS Owner's Manual page 54

The time to scan one line connecting the right edge to the left edge of the
screen horizontally is called Horizontal Cycle and the inverse number of
the Horizontal Cycle is called Horizontal Frequency. Unit : kHz
Vertical Frequency
Like a fluorescent lamp, the screen has to repeat the same image many
times per second to display an image to the user. The frequency of this
repetition is called Vertical Frequency or Refresh Rate. Unit : Hz