( ( ( ( ( ( ( Zero kelvin ) ( -LRB- ( ( ( ( minus 273 ) degrees ) Celsius ) -RRB- ) ) ) , ) or ) ( absolute zero ) ) , ) ( ( is ( ( the temperature ) ( ( at which ) ( ( atomic ( thermal motion ) ) ( would cease ) ) ) ) ) . ) )
(ROOT (S (NP (NP (NP (NNP Zero) (NNP kelvin)) (PRN (-LRB- -LRB-) (ADJP (NP (QP (CC minus) (CD 273)) (NNS degrees)) (JJ Celsius)) (-RRB- -RRB-))) (, ,) (CC or) (NP (JJ absolute) (NN zero)) (, ,)) (VP (VBZ is) (NP (NP (DT the) (NN temperature)) (SBAR (WHPP (IN at) (WHNP (WDT which))) (S (NP (JJ atomic) (JJ thermal) (NN motion)) (VP (MD would) (VP (VB cease))))))) (. .)))
Zero kelvin (minus 273 degrees Celsius), or absolute zero, is the temperature at which atomic thermal motion would cease.
(ROOT (S (NP (NP (DT The) (NN temperature)) (SBAR (WHPP (IN at) (WHNP (WDT which))) (S (NP (DT all) (JJ molecular) (NN motion)) (VP (VBZ has) (VP (VBN ceased)))))) (VP (VBZ is) (VP (VBN called) (NP (JJ absolute) (NN zero)))) (. .)))