( ( AC ( , ( or ( alternating ( current means ) ) ) ) ) ( ( the ( electrical current ) ) ( ( is ( alternating ( directions ( in ( a ( repetitive pattern ) ) ) ) ) ) . ) ) )
(ROOT (S (S (UCP (NP (NNP AC)) (, ,) (CC or) (VP (VBG alternating) (NP (JJ current) (NNS means))))) (NP (DT the) (JJ electrical) (NN current)) (VP (VBZ is) (VP (VBG alternating) (NP (NP (NNS directions)) (PP (IN in) (NP (DT a) (JJ repetitive) (NN pattern)))))) (. .)))
AC, or alternating current means the electrical current is alternating directions in a repetitive pattern.
(ROOT (S (NP (VBG Alternating) (NN current)) (VP (VBZ is) (NP (NP (DT the) (NN term)) (PP (IN for) (NP (JJ electric) (NN current))) (SBAR (WHNP (WDT that)) (S (VP (VBZ keeps) (S (VP (VBG reversing) (NP (NN direction))))))))) (. .)))