The Collaborative International Dictionary of English v.0.48:

Squint \Squint\, v. i. [imp. & p. p. Squinted; p. pr. & vb. n.
   Squinting.]
   1. To see or look obliquely, asquint, or awry, or with a
      furtive glance.
      [1913 Webster]

            Some can squint when they will.       --Bacon.
      [1913 Webster]

   2. (Med.) To have the axes of the eyes not coincident; to be
      cross-eyed.
      [1913 Webster]

   3. To deviate from a true line; to run obliquely.
      [1913 Webster]

   4. To have an indirect bearing, reference, or implication; to
      have an allusion to, or inclination towards, something.

            Yet if the following sentence means anything, it is
            a squinting toward hypnotism.         --The Forum.
      [Webster 1913 Suppl.]

   5. To look with the eyes partly closed.
      [PJC]

The Collaborative International Dictionary of English v.0.48:

Squinting \Squint"ing\ (skw[i^]nt"[i^]ng),
   a. & n. from Squint, v. -- Squint"ing*ly, adv.
   [1913 Webster]

WordNet (r) 3.0 (2006):

squinting
    adj 1: having eyes half closed in order to see better;
           "squinched eyes" [syn: squinched, squinting]

Moby Thesaurus II by Grady Ward, 1.0:

37 Moby Thesaurus words for "squinting":
   agee, agee-jawed, askance, askant, askew, askewgee, asquint,
   astigmatic, awry, blink-eyed, blinking, blinky, catawampous,
   catawamptious, cockeyed, crooked, farsighted, longsighted,
   mope-eyed, myopic, nearsighted, poor-sighted, presbyopic,
   shortsighted, skew, skew-jawed, skewed, slaunchways, squinch-eyed,
   squint-eyed, squinty, strabismal, strabismic, wamper-jawed,
   winking, wry, yaw-ways