noun

• A time period of indeterminate length, generally more than one year.
• (geology) A geochronologic unit of tens to hundreds of millions of years; a subdivision of an eon, and subdivided into periods.
• (astrometry) Initialism of Earth rotation angle (the rotation of the Earth from the Celestial Intermediate Origin that has no instantaneous motion along the equator.)
• (baseball) Initialism of earned run average, a baseball statistic. [(baseball) A statistic in baseball which equals the number of earned runs allowed per nine innings pitched.]
• (electronics) Initialism of electrically reconfigurable array.
• (military) Initialism of explosive reactive armor.
• (UK, military) Initialism of engine room artificer., a Royal Navy position
• (European Union, railways) Initialism of European Railway Agency (called today the European Union Agency for Railways)
• (US) Initialism of Equal Rights Amendment.