accumulation of energy
Webster's Dictionary (GCIDE)
Accumulation \Ac*cu`mu*la"tion\, n. [L. accumulatio; cf. F. accumulation.]
1.The act of accumulating, the state of being accumulated, or that which is accumulated; as, an accumulation of earth, of sand, of evils, of wealth, of honors. [1913 Webster]
2.(Law) The concurrence of several titles to the same proof. [1913 Webster]
Accumulation of energy or power, the storing of energy by means of weights lifted or masses put in motion; electricity stored.
An accumulation of degrees (Eng. Univ.), the taking of several together, or at smaller intervals than usual or than is allowed by the rules. [1913 Webster]