adj

• (of a body of water) Capable of being navigated; deep enough and wide enough to afford passage to vessels.
  "Shanghai is situated on this river, about twelve miles above Woosung; and the river is navigable for steam-boats forty-seven miles higher up—to the point where it issues from the small lake on the south of the canal. Chapoo, the town taken by the British immediately before the attack upon Woosung, is on the north side of the gulf of Che-kiang, about midway between its north cape and its innermost recess. Shanghai is the great emporium of the trade of this district with the tea-provinces on the South, with the province of Shantung and the coast of the Mantchoo Tartars on the North."
• (of a boat) Seaworthy; in a navigable state; steerable.
• (of a balloon) Steerable, dirigible.