( Opaque ( ( means ( ( any material ) ( which ( ( does not ) ( allow ( light ( to ( pass ( through it ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NNP Opaque)) (VP (VBZ means) (NP (NP (DT any) (NN material)) (SBAR (WHNP (WDT which)) (S (VP (VBZ does) (RB not) (VP (VB allow) (ADJP (JJ light) (S (VP (TO to) (VP (VB pass) (PP (IN through) (NP (PRP it))))))))))))) (. .)))
Opaque means any material which does not allow light to pass through it.
(ROOT (S (NP (NNP Opaque)) (VP (VBZ is) (NP (NP (DT the) (NN term)) (PP (IN for) (NP (NN matter))) (SBAR (WHNP (WDT that)) (S (VP (VBZ does) (RB not) (VP (VB let) (NP (DT any) (JJ light) (NN pass)) (PRT (RP through)))))))) (. .)))