The propeller (16) for a fan (14) of a motor vehicle thermal system (10) comprises a bowl (22) for receiving a motor (18) of the propeller (16) and at least one blade (34) connected to the receiving bowl (22), the receiving bowl (22) further comprising: a central member (26) comprising at least one through-orifice (30), a collar (28) extending around the central member (26), the blade (34) extending radially outwards from the collar (28), and at least one rib (36) arranged on a front face of the collar (28), with reference to a direction of flow of an air flow (F) generated by the propeller (16), extending radially outwards so as to have a curved shape oriented in the opposite direction to a direction of rotation of the propeller (16).