Nozzle for a combustion chamber of an engine for providing a fuel-air mixture at a nozzle outlet opening of the nozzle, wherein the nozzle comprises a nozzle main body having the nozzle outlet opening and extending along a nozzle longitudinal axis, and the nozzle main body furthermore comprises at least the following: - at least one first air-guiding duct extending along the nozzle longitudinal axis for conveying air to the nozzle outlet opening, - at least one fuel-guiding duct lying radially further outwards in relation to the first air-guiding duct, with reference to the nozzle longitudinal axis, for conveying fuel to the nozzle outlet opening, and - at least one further, second air-guiding duct lying radially further outwards in relation to the fuel-guiding duct, with reference to the nozzle longitudinal axis, wherein one end (e I) of the fuel-guiding duct, at which end fuel flows out of the fuel-guiding duct in the direction of the air from the first air-guiding duct, lies, with reference to the nozzle longitudinal axis and in the direction of the nozzle outlet opening, in front of the end of the second air-guiding duct, from which end air flows out of the second air-guiding duct in the direction of a mixture of air from the first air-guiding duct and fuel from the fuel-guiding duct, and wherein between the end (e I) of the fuel-guiding duct and the end of the second air-guiding duct, a tapering duct piece is formed on the nozzle with a lateral surface running, with reference to the nozzle longitudinal axis, at an inclination in the axial direction and adjoining a radially outer lateral surface of the fuel-guiding duct, characterized in that - on a radially inner lateral surface of the fuel-guiding duct a concave rounded portion (R DUCT) is provided via which an obliquely radially inwardly pointing portion of the radially inner lateral surface merges into a portion of the radially inner lateral surface, said portion running axially at the end of the fuel-guiding duct, and/or - a diameter of the tapering duct piece at its widest point is greater by a distance 2Δr 1 than a diameter 2r inner of the first air-guiding duct at the end (e I) of the fuel-guiding duct, and the duct piece tapers from its widest point over a length x PF along the nozzle longitudinal axis as far as a diameter 2r outer at the nozzle outlet opening, wherein x PF ≥ 2 Δ r 1. - at least one first air-guiding duct extending along the nozzle longitudinal axis for conveying air to the nozzle outlet opening, - at least one fuel-guiding duct lying radially further outwards in relation to the first air-guiding duct, with reference to the nozzle longitudinal axis, for conveying fuel to the nozzle outlet opening, and - at least one further, second air-guiding duct lying radially further outwards in relation to the fuel-guiding duct, with reference to the nozzle longitudinal axis, wherein one end (e I) of the fuel-guiding duct, at which end fuel flows out of the fuel-guiding duct in the direction of the air from the first air-guiding duct, lies, with reference to the nozzle longitudinal axis and in the direction of the nozzle outlet opening, in front of the end of the second air-guiding duct, from which end air flows out of the second air-guiding duct in the direction of a mixture of air from the first air-guiding duct and fuel from the fuel-guiding duct, and wherein between the end (e I) of the fuel-guiding duct and the end of the second air-guiding duct, a tapering duct piece is formed on the nozzle with a lateral surface running, with reference to the nozzle longitudinal axis, at an inclination in the axial direction and adjoining a radially outer lateral surface of the fuel-guiding duct, characterized in that wherein one end (e I) of the fuel-guiding duct, at which end fuel flows out of the fuel-guiding duct in the direction of the air from the first air-guiding duct, lies, with reference to the nozzle longitudinal axis and in the direction of the nozzle outlet opening, in front of the end of the second air-guiding duct, from which end air flows out of the second air-guiding duct in the direction of a mixture of air from the first air-guiding duct and fuel from the fuel-guiding duct, and wherein between the end (e I) of the fuel-guiding duct and the end of the second air-guiding duct, a tapering duct piece is formed on the nozzle with a lateral surface running, with reference to the nozzle longitudinal axis, at an inclination in the axial direction and adjoining a radially outer lateral surface of the fuel-guiding duct, characterized in that - on a radially inner lateral surface of the fuel-guiding duct a concave rounded portion (R DUCT) is provided via which an obliquely radially inwardly pointing portion of the radially inner lateral surface merges into a portion of the radially inner lateral surface, said portion running axially at the end of the fuel-guiding duct, and/or - a diameter of the tapering duct piece at its widest point is greater by a distance 2Δr 1 than a diameter 2r inner of the first air-guiding duct at the end (e I) of the fuel-guiding duct, and the duct piece tapers from its widest point over a length x PF along the nozzle longitudinal axis as far as a diameter 2r outer at the nozzle outlet opening, wherein x PF ≥ 2 Δ r 1.