liftoff

[lift-awf, -of] /ˈlɪftˌɔf, -ˌɒf/
noun
1.
Aeronautics, Rocketry.
  1. the action of an aircraft in becoming airborne or of a rocket in rising from its launching site under its own power.
  2. the instant when such action occurs.
2.
Informal. the launching or commencement of a project, plan, etc.:
The liftoff of the sales campaign will be next month.
adjective
3.
that removes by lifting off; capable of being lifted off:
a liftoff correction tape for typewriters; magnetized, liftoff nameplates.
Also, lift-off.
Origin
1955-60; noun, adj. use of verb phrase lift off
British Dictionary definitions for lift off

liftoff

/ˈlɪftˌɒf/
noun
1.
the initial movement or ascent of a rocket from its launch pad
2.
the instant at which this occurs
verb
3.
(intransitive, adverb) (of a rocket) to leave its launch pad
Word Origin and History for lift off

liftoff

n.

also lift-off, "vertical take-off of a rocket, etc.," 1956, American English, from lift (v.) + off.

Idioms and Phrases with lift off

lift off

Begin flight, as in The spacecraft was due to lift off at ten o'clock. The off in this idiom means “off the ground.” [ Late 1800s ]