( ( A ( bow wave ) ) ( ( is ( ( ( a ( two dimensional ) ) , ) ( ( V-shaped wave ) ( made ( by ( ( an object ) ( moving ( across ( ( a ( liquid surface ) ) ( at ( ( a ( speed greater ) ) ( than ( the ( wave speed ) ) ) ) ) ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (DT A) (NN bow) (NN wave)) (VP (VBZ is) (NP (NP (DT a) (CD two) (NN dimensional)) (, ,) (NP (NP (JJ V-shaped) (NN wave)) (VP (VBN made) (PP (IN by) (NP (NP (DT an) (NN object)) (VP (VBG moving) (PP (IN across) (NP (NP (DT a) (JJ liquid) (NN surface)) (PP (IN at) (NP (NP (DT a) (NN speed) (JJR greater)) (PP (IN than) (NP (DT the) (NN wave) (NN speed)))))))))))))) (. .)))
A bow wave is a two dimensional, V-shaped wave made by an object moving across a liquid surface at a speed greater than the wave speed.
(ROOT (S (NP (DT A) (NN bow) (NN wake)) (VP (VBZ is) (VP (VBN created) (SBAR (WHADVP (WRB when)) (S (NP (DT the) (NN wave) (NN source)) (VP (VBZ moves) (ADVP (RBR faster)) (PP (IN than) (NP (DT the) (NN wave) (NN propagation) (NN speed)))))))) (. .)))