The Collaborative International Dictionary of English v.0.48:

Difficulty \Dif"fi*cul*ty\, n.; pl. Difficulties. [L.
   difficultas, fr. difficilis difficult; dif- = dis- + facilis
   easy: cf. F. difficult['e]. See Facile.]
   1. The state of being difficult, or hard to do; hardness;
      arduousness; -- opposed to easiness or facility; as,
      the difficulty of a task or enterprise; a work of
      difficulty.
      [1913 Webster]

            Not being able to promote them [the interests of
            life] on account of the difficulty of the region.
                                                  --James Byrne.
      [1913 Webster]

   2. Something difficult; a thing hard to do or to understand;
      that which occasions labor or perplexity, and requires
      skill and perseverance to overcome, solve, or achieve; a
      hard enterprise; an obstacle; an impediment; as, the
      difficulties of a science; difficulties in theology.
      [1913 Webster]

            They lie under some difficulties by reason of the
            emperor's displeasure.                --Addison.
      [1913 Webster]

   3. A controversy; a falling out; a disagreement; an
      objection; a cavil.
      [1913 Webster]

            Measures for terminating all local difficulties.
                                                  --Bancroft.
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   4. Embarrassment of affairs, especially financial affairs; --
      usually in the plural; as, to be in difficulties.
      [1913 Webster]

            In days of difficulty and pressure.   --Tennyson.

   Syn: Impediment; obstacle; obstruction; embarrassment;
        perplexity; exigency; distress; trouble; trial;
        objection; cavil. See Impediment.
        [1913 Webster]

Moby Thesaurus II by Grady Ward, 1.0:

50 Moby Thesaurus words for "difficulties":
   adverse circumstances, adversity, affliction, aggravation,
   annoyance, blight, broken fortune, bummer, care, cross, curse,
   difficulty, distress, downer, embarrassment, genteel poverty,
   hard knocks, hard life, hard lot, hard pinch, hardcase, hardship,
   impecuniosity, impecuniousness, insolvency, irritation,
   light purse, narrow means, plight, poorness, poverty, predicament,
   pressure, rigor, sea of troubles, slender means,
   straitened circumstances, straits, stress, stress of life,
   tight squeeze, trial, tribulation, trouble, troubles,
   unprosperousness, vale of tears, vicissitude, voluntary poverty,
   vows of poverty