megawatt hours
Definition of 'megawatt hour'. Word Frequency. megawatt hour (ËmÉÉ¡ÉËwÉt aÊÉ) noun. a unit of energy equal to the work done by a power of a million watts in one hour. Electricity prices have fallen by 10% to Â£20.80 per megawatt hour over the past 12 months. Trends of 'megawatt hour'.