( ( ( alternating ( current ( -LRB- ( AC -RRB- ) ) ) ) ( ( An ( electric current ) ) ( that ( ( reverses ( its direction ) ) ( at ( regularly ( recurring intervals ) ) ) ) ) ) ) . )
(ROOT (NP (NP (RB alternating) (JJ current) (PRN (-LRB- -LRB-) (NP (NNP AC)) (-RRB- -RRB-))) (NP (NP (DT An) (JJ electric) (NN current)) (SBAR (WHNP (WDT that)) (S (VP (VBZ reverses) (NP (PRP$ its) (NN direction)) (PP (IN at) (NP (JJ regularly) (VBG recurring) (NNS intervals))))))) (. .)))
alternating current (AC) An electric current that reverses its direction at regularly recurring intervals.
(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))))))))) (. .)))