countdown

Short definition from Wiktionary

Noun

1. 1
   A count backward in fixed units to the time of some event, especially the launch of a space vehicle.
2. 2
   The acts of preparation carried out during this period.
3. 3
   A radio or television program counting down the top songs of a given week, usually in reverse order and ending with the number one song.

Verb

1. 1
   To count down.