The Collaborative International Dictionary of English v.0.48:

Undiscerning \Un`dis*cern"ing\, n.
   Want of discernment. [R.] --Spectator.
   [1913 Webster]
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Undiscerning \Undiscerning\
   See discerning.

WordNet (r) 3.0 (2006):

undiscerning
    adj 1: lacking discernment [ant: discerning]

Moby Thesaurus II by Grady Ward, 1.0:

70 Moby Thesaurus words for "undiscerning":
   ableptical, amaurotic, benighted, bereft of light, blind,
   blindfold, blindfolded, color-blind, dark, dim-sighted, eyeless,
   hemeralopic, ill-advised, ill-considered, ill-contrived,
   ill-devised, ill-gauged, ill-judged, imperceptive, impercipient,
   impolitic, imprudent, in darkness, inadvisable, inconsiderate,
   indiscreet, inexpedient, injudicious, insensate, insensible,
   irrational, mind-blind, mindless, misadvised, misguided, myopic,
   nearsighted, nonunderstanding, nyctalopic, purblind, rayless,
   reasonless, reckless, senseless, shortsighted, sightless,
   spiritually blind, stark blind, stone-blind, thoughtless,
   unadvised, unapprehending, uncomprehending, unconsidered,
   unenlightened, unforeseeing, unobserving, unperceiving,
   unperceptive, unreasonable, unreflecting, unreflective, unseeing,
   unsensible, unsound, unthinking, unthoughtful, unwise, visionless,
   witless