The Collaborative International Dictionary of English v.0.48:

Diligence \Di`li*gence"\, n. [F.]
   A four-wheeled public stagecoach, used in France.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Diligence \Dil"i*gence\, n. [F. diligence, L. diligentia.]
   1. The quality of being diligent; carefulness; careful
      attention; -- the opposite of negligence.
      [1913 Webster]

   2. Interested and persevering application; devoted and
      painstaking effort to accomplish what is undertaken;
      assiduity in service.
      [1913 Webster]

            That which ordinary men are fit for, I am qualified
            in; and the best of me is diligence.  --Shak.
      [1913 Webster]

   3. (Scots Law) Process by which persons, lands, or effects
      are seized for debt; process for enforcing the attendance
      of witnesses or the production of writings.
      [1913 Webster]

   To do one's diligence, give diligence, use diligence,
      to exert one's self; to make interested and earnest
      endeavor.
      [1913 Webster]

            And each of them doth all his diligence
            To do unto the fest['e] reverence.    --Chaucer.

   Syn: Attention; industry; assiduity; sedulousness;
        earnestness; constancy; heed; heedfulness; care;
        caution. -- Diligence, Industry. Industry has the
        wider sense of the two, implying an habitual devotion to
        labor for some valuable end, as knowledge, property,
        etc. Diligence denotes earnest application to some
        specific object or pursuit, which more or less directly
        has a strong hold on one's interests or feelings. A man
        may be diligent for a time, or in seeking some favorite
        end, without meriting the title of industrious. Such was
        the case with Fox, while Burke was eminent not only for
        diligence, but industry; he was always at work, and
        always looking out for some new field of mental effort.
        [1913 Webster]

              The sweat of industry would dry and die,
              But for the end it works to.        --Shak.
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              Diligence and accuracy are the only merits which
              an historical writer ascribe to himself. --Gibbon.
        [1913 Webster]

WordNet (r) 3.0 (2006):

diligence
    n 1: conscientiousness in paying proper attention to a task;
         giving the degree of care required in a given situation
    2: persevering determination to perform a task; "his diligence
       won him quick promotions"; "frugality and industry are still
       regarded as virtues" [syn: diligence, industriousness,
       industry]
    3: a diligent effort; "it is a job requiring serious
       application" [syn: application, diligence]

Moby Thesaurus II by Grady Ward, 1.0:

92 Moby Thesaurus words for "diligence":
   advertence, advertency, alertness, application, ardor, assiduity,
   assiduousness, attention, attention span, attentiveness, awareness,
   bookishness, bulldog tenacity, care, concentration, consciousness,
   consideration, constancy, dogged perseverance, doggedness, ear,
   earnestness, endurance, energeticalness, energy, engrossment,
   fervor, fidelity, heed, heedfulness, indefatigability,
   industriousness, industry, insistence, insistency, intentiveness,
   intentness, laboriousness, loyalty, mindfulness, note, notice,
   observance, observation, obstinacy, pains, painstaking,
   painstakingness, patience, patience of Job, permanence,
   perseverance, persistence, persistency, pertinaciousness,
   pertinacity, plodding, plugging, preoccupation, regard,
   regardfulness, relentlessness, remark, resolution, respect,
   scholarliness, scholarship, sedulity, sedulousness,
   single-mindedness, singleness of purpose, slogging, stability,
   stamina, staying power, steadfastness, steadiness,
   stick-to-itiveness, strenuousness, stubbornness, studiousness,
   tenaciousness, tenacity, thoroughgoingness, thoroughness, thought,
   tirelessness, unremittingness, unsparingness, unswerving attention,
   vehemence, zealousness



Bouvier's Law Dictionary, Revised 6th Ed (1856):

DILIGENCE. In Scotland, there are certain forms of law, whereby a creditor
endeavors to make good his payment, either by affecting the person of his
debtor, or by securing the subjects belonging to him from alienation, or by
carrying the property of these subjects to himself. They are either real or
personal.
     2. Real diligence is that which is proper to heritable or real rights,.
and of this kind there are two sorts: 1. Inhibitions. 2. Adjudication, which
the law has substituted in the place of apprising.
     3. Personal diligence is that by which the person of the debtor may be
secured, or his personal estate affected. Ersk. Pr. L. Scotl. B. 2, t. 11,
s. 1.



Bouvier's Law Dictionary, Revised 6th Ed (1856):

DILIGENCE, contracts. The doing things in proper time.
     2. It may be divided into three degrees, namely: ordinary diligence,
extraordinary diligence, and slight diligence. It is the reverse of
negligence. (q.v.) Under that article is shown what degree of negligence,
or want of diligence, will make a party to a contract responsible to the
other. Vide Story, Bailm. Index h.t.; Ayl. Pand. 113 1 Miles, Rep. 40.