The Collaborative International Dictionary of English v.0.48:

Inkling \In"kling\, n.
   A hint; an intimation.
   [1913 Webster]

         The least inkling or glimpse of this island. --Bacon.
   [1913 Webster]

         They had some inkling of secret messages. --Clarendon.
   [1913 Webster]

WordNet (r) 3.0 (2006):

inkling
    n 1: a slight suggestion or vague understanding; "he had no
         inkling what was about to happen" [syn: inkling,
         intimation, glimmering, glimmer]

Moby Thesaurus II by Grady Ward, 1.0:

61 Moby Thesaurus words for "inkling":
   bare suggestion, broad hint, clue, cue, dash, gentle hint, gesture,
   glimmer, glimmering, half an idea, hazy idea, hint, idea,
   implication, impression, index, indication, infusion, innuendo,
   insinuation, intimation, kick, look, mere notion, nod, notion,
   nudge, prompt, sauce, scent, seasoning, shade, sign, signal, smack,
   sneaking suspicion, soupcon, spice, spoor, sprinkling, suggestion,
   suspicion, symptom, taint, telltale, tempering, thought, tinct,
   tincture, tinge, tint, tip, tip-off, touch, trace, track,
   vague idea, vestige, whisper, wind, wink