( ( A groin ) ( ( is ( ( wall ( of ( ( rocks or ) concrete ) ) ) ( that ( ( ( juts out ) ( into ( the ( ocean perpendicular ) ) ) ) ( to ( the shore ) ) ) ) ) ) . ) )
(ROOT (S (NP (DT A) (NN groin)) (VP (VBZ is) (NP (NP (NN wall)) (PP (IN of) (NP (NNS rocks) (CC or) (NN concrete))) (SBAR (WHNP (WDT that)) (S (VP (VBZ juts) (PRT (RP out)) (PP (IN into) (NP (DT the) (NN ocean) (NN perpendicular))) (PP (TO to) (NP (DT the) (NN shore)))))))) (. .)))
A groin is wall of rocks or concrete that juts out into the ocean perpendicular  to the shore.
(ROOT (S (NP (NP (DT A) (NN wall)) (PP (IN of) (NP (NP (NNS rocks)) (CC or) (NP (JJ concrete) (DT a))))) (VP (VBD called) (NP (DT a) (NN groin))) (. .)))