( ( ( Thrust The ) ( ( ( pushing or ) pulling ) force ) ) ( ( developed ( by ( ( ( an ( aircraft engine ) ) or ) ( a ( rocket engine ) ) ) ) ) . ) )
(ROOT (S (NP (NP (NNP Thrust) (NNP The)) (VP (VBG pushing) (CC or) (VBG pulling) (NP (NN force)))) (VP (VBD developed) (PP (IN by) (NP (NP (DT an) (NN aircraft) (NN engine)) (CC or) (NP (DT a) (NN rocket) (NN engine))))) (. .)))
Thrust The pushing or pulling force developed by an aircraft engine or a rocket engine.
(ROOT (S (NP (NNP Thrust)) (VP (VBZ is) (NP (NP (DT the) (NN force)) (VP (VBG pushing) (NP (DT a) (NN rocket))))) (. .)))