( ( Nuclear fusion ) ( ( is ( when ( ( ( ( two or ) more ) ( light nuclei ) ) ( ( ( join ( together ( to ( form ( a ( heavier nucleus ) ) ) ) ) ) , ) ( ( releasing energy ) ( in ( the process ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (JJ Nuclear) (NN fusion)) (VP (VBZ is) (SBAR (WHADVP (WRB when)) (S (NP (QP (CD two) (CC or) (JJR more)) (JJ light) (NNS nuclei)) (VP (VBP join) (S (ADVP (RB together)) (VP (TO to) (VP (VB form) (NP (DT a) (JJR heavier) (NN nucleus))))) (, ,) (S (VP (VBG releasing) (NP (NN energy)) (PP (IN in) (NP (DT the) (NN process))))))))) (. .)))
Nuclear fusion is when two or more light nuclei join together to form a heavier nucleus, releasing energy in the process.
(ROOT (S (PP (IN In) (NP (DT the) (JJ nuclear) (NN fusion) (NN process))) (, ,) (NP (CD two) (JJ light) (NNS nuclei)) (VP (VBP combine) (S (VP (TO to) (VP (VB produce) (NP (NP (DT a) (JJR heavier) (NN nucleus)) (CC and) (NP (JJ great) (NN energy))))))) (. .)))