Ma'anar ƙamus na kalmar "rudder" wani lebur ne, yanki mai motsi a bayan jirgin ruwa ko jirgin sama, ana amfani da shi wajen tuƙi da jagorantar tafiyarsa. Yawanci ruwa ne ko allo a tsaye wanda ke rataye a gefensa na kasa zuwa madaidaicin jirgin ruwa ko kuma zuwa wutsiyar jirgin sama. Ana sarrafa mashin ɗin ta hanyar sitiyari, kamar tiller ko dabaran, ana amfani da shi don daidaita alkiblar jirgin ko jirgin ta hanyar canza kusurwar ruwan tudu.