count down
Numbers toward zero
Count down is to recite numbers in descending order, typically toward zero: The crowd counted down to midnight.
The practice comes from rocket launches, where reaching zero triggers ignition.
Figuratively, counting down means eagerly anticipating something: I'm counting down the days until vacation.
The noun countdown is one word.
timer
Duration-tracking mechanism
zero · final · launch · blastoff · liftoff · ignition · rocket · sequence · decrement · backward
excitement
State of eager enthusiasm
imminent · impending · readiness · preparation · deadline · moments · thrill · suspense · waiting · buildup