The Collaborative International Dictionary of English v.0.48:

Checker \Check"er\ (ch[e^]k"[~e]r), n. [From Check, v. t.]
   One who checks.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Checker \Check"er\ (ch[e^]k"[~e]r), v. t. [imp. & p. p.
   Checkered (ch[e^]k"[~e]rd); p. pr. & vb. n. Checkering.]
   [From OF. eschequier a chessboard, F. ['e]chiquier. See
   Check, n., and cf. 3d Checker.]
   1. To mark with small squares like a checkerboard, as by
      crossing stripes of different colors.
      [1913 Webster]

   2. To variegate or diversify with different qualities,
      colors, scenes, or events; esp., to subject to frequent
      alternations of prosperity and adversity.
      [1913 Webster]

            Our minds are, as it were, checkered with truth and
            falsehood.                            --Addison.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Checker \Check"er\, n. [OF. eschequier. See Checker, v. t.]
   1. A piece in the game of draughts or checkers.
      [1913 Webster]

   2. A pattern in checks; a single check.
      [1913 Webster]

   3. Checkerwork.
      [1913 Webster]

   Note: This word is also written chequer.
         [1913 Webster]

WordNet (r) 3.0 (2006):

checker
    n 1: an attendant who checks coats or baggage
    2: one who checks the correctness of something
    3: one of the flat round pieces used in playing the game of
       checkers [syn: checker, chequer]
    v 1: mark into squares or draw squares on; draw crossed lines on
         [syn: check, checker, chequer]
    2: variegate with different colors, shades, or patterns [syn:
       checker, chequer]

Moby Thesaurus II by Grady Ward, 1.0:

79 Moby Thesaurus words for "checker":
   alter, ameliorate, band, bar, be changed, be converted into,
   be renewed, bespangle, bespeckle, bespot, blotch, bottom out,
   break, change, check, chop, chop and change, come about,
   come around, come round, dapple, degenerate, deteriorate, deviate,
   diverge, diversify, dot, flake, fleck, flop, freckle, harlequin,
   haul around, improve, iris, jibe, maculate, marble, marbleize,
   meliorate, mitigate, modulate, motley, mottle, mutate, pepper,
   polychrome, polychromize, rainbow, revive, shift, spangle, speck,
   speckle, splotch, spot, sprinkle, stigmatize, stipple, streak,
   striate, stripe, stud, swerve, tack, take a turn, tattoo,
   tessellate, turn, turn aside, turn into, turn the corner,
   undergo a change, variegate, vary, veer, vein, warp, worsen