The Collaborative International Dictionary of English v.0.48:

Cotter \Cot"ter\, v. t.
   To fasten with a cotter.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Cottier \Cot"ti*er\ (-t[i^]*[~e]r), n. [OF. cotier. See
   Coterie, and cf. Cotter.]
   In Great Britain and Ireland, a person who hires a small
   cottage, with or without a plot of land. Cottiers commonly
   aid in the work of the landlord's farm. [Written also
   cottar and cotter.]
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Cotter \Cot"ter\, Cottar \Cot"tar\ (k?t"t?r), n. [LL. cotarius,
   cottarius, coterius. See Cot.]
   A cottager; a cottier. --Burns.
   [1913 Webster]

         Through Sandwich Notch the West Wind sang
         Good morrow to the cotter.               --Whittier.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Cotter \Cot"ter\ (k[o^]t"t[~e]r), n.
   1. A piece of wood or metal, commonly wedge-shaped, used for
      fastening together parts of a machine or structure. It is
      driven into an opening through one or all of the parts.

   Note: [See Illust.] In the United States a cotter is commonly
         called a key.
         [1913 Webster]

   2. A toggle.
      [1913 Webster]

WordNet (r) 3.0 (2006):

cotter
    n 1: a peasant farmer in the Scottish Highlands [syn: cotter,
         cottar]
    2: a medieval English villein [syn: cotter, cottier]
    3: fastener consisting of a wedge or pin inserted through a slot
       to hold two other pieces together [syn: cotter, cottar]