1. seashore; slope. move alongside of; sail alongside a coast; slide or run downhill; skate or ski; move under acquired momentum. coastcoast , v. i. [imp. & p. p. coasted; p. pr. & vb. n. coasting.] [oe. costien, costeien, costen, of. costier, costoier, f. cÃ'toyer, fr. of. coste coast, f. cÃ'te. see: coast, n.]