aritta : [nt.] a rudder. (adj.), not empty or futile.

A.P. Buddhadatta Mahathera, Concise Pali-English and English-Pali Dictionary [available as digital version from Metta Net, Sri Lanka]

Aritta (nt.) [Vedic aritra, Idg. *ere to row (Sk. ṛ to move); cf. Gr. e)re/ssw to row, e)retmo/s rudder, Lat. remus, Ohg. ruodar = rudder; Ags. rōwan = E. row] a rudder. Usually in combn. with piya (phiya) oar, as piyârittaŋ (phiy˚) oar & rudder, thus at S i.103 (T. piya˚, v. l. phiya˚); A ii.201 (piya˚); J iv.164 (T. piya˚, v.l. phiya˚); Sn 321 (piya +; SnA 330 phiya = dabbi -- padara, aritta = veḷudaṇḍa). DhsA 149.

Pali-English Dictionary, TW Rhys Davids, William Stede,