The Collaborative International Dictionary of English v.0.48:

Spud \Spud\ (sp[u^]d), n. [Cf. Dan. spyd a spear.]
   1. A sharp, narrow spade, usually with a long handle, used by
      farmers for digging up large-rooted weeds; a similarly
      shaped implement used for various purposes.
      [1913 Webster]

            My spud these nettles from the stone can part.
                                                  --Swift.
      [1913 Webster]

   2. A dagger. [Obs.] --Holland.
      [1913 Webster]

   3. Anything short and thick; specifically, a piece of dough
      boiled in fat. [Local, U.S.]
      [1913 Webster]

   4. A potato. [Colloq.]
      [Webster 1913 Suppl.]

WordNet (r) 3.0 (2006):

spud
    n 1: an edible tuber native to South America; a staple food of
         Ireland [syn: potato, white potato, Irish potato,
         murphy, spud, tater]
    2: a sharp hand shovel for digging out roots and weeds [syn:
       spud, stump spud]
    v 1: initiate drilling operations, as for petroleum; "The well
         was spudded in April"
    2: produce buds, branches, or germinate; "the potatoes sprouted"
       [syn: shoot, spud, germinate, pullulate, bourgeon,
       burgeon forth, sprout]