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Meaning of sustainer

sus•tain•er

Pronunciation: (su-stā'nur), [key]
— n.
  1. a person or thing that sustains.
    1. any stage of a multistage rocket or guided missile that sustains flight after the burnout of the booster.
    2. the rocket engine or cluster of engines contained in such a stage.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.
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