电气 is a technical noun meaning 'electrical power' or 'electrical (as a field)'. It differs from the everyday word 电 (diàn, 'electricity') in that 电气 is used mainly in formal or technical contexts, especially as a modifier in compounds such as 电气化 ('electrification'), 电气系统 ('electrical system'), and 电气工程 ('electrical engineering'). It appears as a noun but often functions attributively before another noun.