Source : Webster's Revised Unabridged Dictionary (1913)

   5. (Mach.) A skeleton, or frame, having radiating arms or
      members, often connected by crosspieces; as, a casting
      forming the hub and spokes to which the rim of a fly wheel
      or large gear is bolted; the body of a piston head; a
      frame for strengthening a core or mold for a casting, etc.

   {Spider ant}. (Zo["o]l.) Same as {Solitary ant}, under
      {Solitary}.

   {Spider crab} (Zo["o]l.), any one of numerous species of
      maioid crabs having a more or less triangular body and ten
      long legs. Some of the species grow to great size, as the
      great Japanese spider crab ({Macrocheira Kempferi}),
      measuring sometimes more than fifteen feet across the legs
      when they are extended.

   {Spider fly} (Zo["o]l.), any one of numerous species of
      parasitic dipterous insects of the family
      {Hippoboscid[ae]}. They are mostly destitute of wings, and
      live among the feathers of birds and the hair of bats.
      Called also {bird tick}, and {bat tick}.

   {Spider hunter} (Zo["o]l.), any one of several species of
      East Indian sunbirds of the genus {Arachnothera}.

   {Spider lines}, filaments of a spider's web crossing the
      field of vision in optical instruments; -- used for
      determining the exact position of objects and making
      delicate measurements. Fine wires, silk fibers, or lines
      on glass similarly placed, are called spider lines.

   {Spider mite}. (Zo["o]l.)
      (a) Any one of several species of parasitic mites of the
          genus {Argas} and allied genera. See {Argas}.
      (b) Any one of numerous small mites injurious to plants.
          

   {Spider monkey} (Zo["o]l.), any one of numerous species of
      South American monkeys of the genus {Ateles}, having very
      long legs and a long prehensile tail.

   {Spider orchis} (Bot.), a European orchidaceous plant
      ({Ophrys aranifera}), having flowers which resemble
      spiders.

   {Spider shell} (Zo["o]l.), any shell of the genus
      {Pteroceras}. See {Pteroceras}.

Source : WordNet®

spider crab
     n : any of numerous crabs with very long legs and small
         triangular bodies