Artificial intelligent assistant

retro-engine

ˈretro-engine Astronautics.
  Also as one word.
  [f. retro- + engine n.]
  = retro-rocket b.

1967 Britannica Bk. of Year 804/1 Retro-engine, retro-rocket. 1971 New Scientist 6 May 305 Each Mariner..carries to Mars..about 1000 lbs of fuel for the 14-minute retroengine burn needed to slow it to the requisite orbital speed. 1977 Sci. Amer. Nov. 52/1 With the help of its retroengines and parachute it dropped to the surface of Mars.

Oxford English Dictionary

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