noun.
The illuminating power of a candle; specifically, the illuminating power of a candle of determinate composition and rate of burning, taken as a unit in estimating the luminosity of any illuminating agent: as, a gas-jet of 25 candle-power.
the GNU version of the Collaborative International Dictionary of English
luminous intensity; illuminating power, as of a lamp, or gas flame, measured in candelas, referring to the light of a standard candle.