( ( pupil ( ( The opening ) ( in ( ( the iris ) ( of ( ( the eye ) ( that ( admits light ) ) ) ) ) ) ) ) . )
(ROOT (S (VP (VB pupil) (NP (NP (DT The) (NN opening)) (PP (IN in) (NP (NP (DT the) (NNS iris)) (PP (IN of) (NP (NP (DT the) (NN eye)) (SBAR (WHNP (WDT that)) (S (VP (VBZ admits) (ADJP (JJ light))))))))))) (. .)))
pupil The opening in the iris of the eye that admits light.
(ROOT (S (NP (DT The) (NN pupil)) (VP (VBZ is) (NP (NP (DT the) (NN opening)) (PP (IN in) (NP (NP (DT the) (NN front)) (PP (IN of) (NP (DT the) (NN eye))))))) (. .)))