A component defines a blade or a vane for a rotor rotatable about a rotary axis (x). An inner space (10) of the component is limited by first and second walls (12), and forms a passage for a cooling fluid. First and second ribs (21, 22) project form the first and second walls, respectively, and extend in parallel to each other to form channels for the fluid from a leading end to a trailing end ofthe ribs. The ribs extend along a first and a third direction, respectively, in the proximity of the leading end and along a second direction and fourth direction, respectively, in the proximity of the trailing end. The first direction is inclined in relation to the second direction. The third direction is inclined in relation to the fourth direction. The first direction intersects with the thirddirection. The ribs extend from the leading end to the trailing end along a continuously curved path.