The Collaborative International Dictionary of English v.0.48:

Promontory \Prom"on*to*ry\, n.; pl. Promontories. [ L.
   promonturium, promunturium; pro before + mons, montis,
   mountain: cf. F. promontoire. See Mount, n.]
   [1913 Webster]
   1. (Phys. Geog.) A high point of land or rock projecting into
      the sea beyond the line of coast; a headland; a high cape.
      [1913 Webster]

            Like one that stands upon a promontory. --Shak.
      [1913 Webster]

   2. (Anat.) A projecting part. Especially:
      (a) The projecting angle of the ventral side of the sacrum
          where it joins the last lumbar vertebra.
      (b) A prominence on the inner wall of the tympanum of the
          ear.
          [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Doubling \Dou"bling\, n.
   1. The act of one that doubles; a making double;
      reduplication; also, that which is doubled.
      [1913 Webster]

   2. A turning and winding; as, the doubling of a hunted hare;
      shift; trick; artifice. --Dryden.
      [1913 Webster]

   3. (Her.) The lining of the mantle borne about the shield or
      escutcheon.
      [1913 Webster]

   4. The process of redistilling spirits, to improve the
      strength and flavor.
      [1913 Webster]

   5. raising the stakes in a game, such as a card game or
      backgammon, by a factor of 2.

   Syn: double.
        [WordNet 1.5]

   Doubling a cape, promontory, etc. (Naut.), sailing around
      or passing beyond a cape, promontory, etc.
      [1913 Webster]

WordNet (r) 3.0 (2006):

promontory
    n 1: a natural elevation (especially a rocky one that juts out
         into the sea) [syn: promontory, headland, head,
         foreland]

Moby Thesaurus II by Grady Ward, 1.0:

21 Moby Thesaurus words for "promontory":
   beak, bill, breakwater, cape, chersonese, coral reef, delta,
   foreland, head, headland, hook, mull, naze, ness, peninsula, point,
   reef, sandspit, spit, spur, tongue