Lewis & Short

rĕmulcum (rymulcum, acc. to the Gr., Amm. 18, 5, 6), i (for the most part only in abl.), n. [ῤυμουλκέω], nautical t. t., a tow-rope, or any other contrivance for towing: remulcum funis, quo deligata navis magnā trahitur vice remi, Isid. Orig. 19, 4, 8: remulco est, cum scaphae remis navis magna trahitur, Fest. p. 279 Müll.: navem remulco abstraxit, Caes. B. C. 2, 23 fin.: submersam navim remulco adduxit, id. ib. 3, 40: naves onerarias remulco Alexandriam deducit, Auct. B. Alex. 11 fin.: navem remulco trahere, Liv. 25, 30; 32, 16.
Here prob. belongs the fragment of Sisenna: in altum remulco trahit, Sisenn. ap. Non. 57, 29 (where Nonius erroneously assumes a verb, remulco, āre; cf. supra, the article of Festus, where also remulco forms the heading); Valgius ap. Isid. l. l.; Aus. Idyll. 10, 41; id. Ep. 2, 9; Paul. Nol. Ep. 49.
Prov.: non contis nec rymulco, ut aiunt, sed velificatione plenā in rempublicam ferebantur, Amm. 18, 5, 6.