hydroelectric
Concise Oxford English Dictionary © 2008 Oxford University Press:
hydroelectric/hʌɪdrəʊɪˈlektrɪk/
▶adjective relating to or denoting the generation of electricity using flowing water to drive a turbine which powers a generator.
– derivatives
hydroelectricity noun.
hydroelectricity noun.
'hydroelectric' also found in these Oxford entries:

