countdown

• POS: Noun, Verb (usu participle)
• HYPHEN: count=down

OXFORD DICTIONARY

countdown, n.
1 a the act of counting down, esp. at the launching of a rocket etc. b the procedures carried out during this time.
2 the final moments before any significant event.

ROGET THESAURUS

countdown

Propulsion

N propulsion, projection, propelment, vis a tergo, force from behind, push, shove, ejaculate, ejection, throw, fling, toss, shot, discharge, shy, launch, release, projectiles, ballistics, archery, propeller, screw, twin screws, turbine, jet engine, missile, projectile, ball, discus, quoit, brickbat, shot, arrow, gun, ballista, countdown, windup, shooter, shot, archer, toxophilite, bowman, rifleman, marksman, good shot, crack shot, sharpshooter, propelled, propelling, propulsive, projectile.