means The electrical potential difference between two points, measured in volts, that drives current through a circuit.

from Named for Alessandro Volta, the Italian physicist who built the first true battery — the 'voltaic pile' — around the turn of the 19th century. His surname became the unit (the volt), and 'voltage' simply piles the '-age' suffix on top, the same ending that turns a thing into a measure or quantity, as in 'mileage' or 'wattage.' So every time you say it, you're quietly crediting a man who stacked discs of metal and brine and proved electricity could be made to flow.