The Collaborative International Dictionary of English v.0.48:

Heart \Heart\ (h[aum]rt), n. [OE. harte, herte, heorte, AS.
   heorte; akin to OS. herta, OFies. hirte, D. hart, OHG. herza,
   G. herz, Icel. hjarta, Sw. hjerta, Goth. ha['i]rt[=o], Lith.
   szirdis, Russ. serdtse, Ir. cridhe, L. cor, Gr. kardi`a,
   kh^r. [root]277. Cf. Accord, Discord, Cordial, 4th
   Core, Courage.]
   1. (Anat.) A hollow, muscular organ, which, by contracting
      rhythmically, keeps up the circulation of the blood.
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            Why does my blood thus muster to my heart! --Shak.
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   Note: In adult mammals and birds, the heart is
         four-chambered, the right auricle and ventricle being
         completely separated from the left auricle and
         ventricle; and the blood flows from the systemic veins
         to the right auricle, thence to the right ventricle,
         from which it is forced to the lungs, then returned to
         the left auricle, thence passes to the left ventricle,
         from which it is driven into the systemic arteries. See
         Illust. under Aorta. In fishes there are but one
         auricle and one ventricle, the blood being pumped from
         the ventricle through the gills to the system, and
         thence returned to the auricle. In most amphibians and
         reptiles, the separation of the auricles is partial or
         complete, and in reptiles the ventricles also are
         separated more or less completely. The so-called lymph
         hearts, found in many amphibians, reptiles, and birds,
         are contractile sacs, which pump the lymph into the
         veins.
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   2. The seat of the affections or sensibilities, collectively
      or separately, as love, hate, joy, grief, courage, and the
      like; rarely, the seat of the understanding or will; --
      usually in a good sense, when no epithet is expressed; the
      better or lovelier part of our nature; the spring of all
      our actions and purposes; the seat of moral life and
      character; the moral affections and character itself; the
      individual disposition and character; as, a good, tender,
      loving, bad, hard, or selfish heart.
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            Hearts are dust, hearts' loves remain. --Emerson.
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   3. The nearest the middle or center; the part most hidden and
      within; the inmost or most essential part of any body or
      system; the source of life and motion in any organization;
      the chief or vital portion; the center of activity, or of
      energetic or efficient action; as, the heart of a country,
      of a tree, etc.
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            Exploits done in the heart of France. --Shak.
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            Peace subsisting at the heart
            Of endless agitation.                 --Wordsworth.
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   4. Courage; courageous purpose; spirit.
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            Eve, recovering heart, replied.       --Milton.
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            The expelled nations take heart, and when they fly
            from one country invade another.      --Sir W.
                                                  Temple.
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   5. Vigorous and efficient activity; power of fertile
      production; condition of the soil, whether good or bad.
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            That the spent earth may gather heart again.
                                                  --Dryden.
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   6. That which resembles a heart in shape; especially, a
      roundish or oval figure or object having an obtuse point
      at one end, and at the other a corresponding indentation,
      -- used as a symbol or representative of the heart.
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   7. One of the suits of playing cards, distinguished by the
      figure or figures of a heart; as, hearts are trumps.
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   8. Vital part; secret meaning; real intention.
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            And then show you the heart of my message. --Shak.
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   9. A term of affectionate or kindly and familiar address. "I
      speak to thee, my heart." --Shak.
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   Note: Heart is used in many compounds, the most of which need
         no special explanation; as, heart-appalling,
         heart-breaking, heart-cheering, heart-chilled,
         heart-expanding, heart-free, heart-hardened,
         heart-heavy, heart-purifying, heart-searching,
         heart-sickening, heart-sinking, heart-sore,
         heart-stirring, heart-touching, heart-wearing,
         heart-whole, heart-wounding, heart-wringing, etc.
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   After one's own heart, conforming with one's inmost
      approval and desire; as, a friend after my own heart.

            The Lord hath sought him a man after his own heart.
                                                  --1 Sam. xiii.
                                                  14.

   At heart, in the inmost character or disposition; at
      bottom; really; as, he is at heart a good man.

   By heart, in the closest or most thorough manner; as, to
      know or learn by heart. "Composing songs, for fools to get
      by heart" (that is, to commit to memory, or to learn
      thoroughly). --Pope.

   to learn by heart, to memorize.

   For my heart, for my life; if my life were at stake. [Obs.]
      "I could not get him for my heart to do it." --Shak.

   Heart bond (Masonry), a bond in which no header stone
      stretches across the wall, but two headers meet in the
      middle, and their joint is covered by another stone laid
      header fashion. --Knight.

   Heart and hand, with enthusiastic co["o]peration.

   Heart hardness, hardness of heart; callousness of feeling;
      moral insensibility. --Shak.

   Heart heaviness, depression of spirits. --Shak.

   Heart point (Her.), the fess point. See Escutcheon.

   Heart rising, a rising of the heart, as in opposition.

   Heart shell (Zool.), any marine, bivalve shell of the genus
      Cardium and allied genera, having a heart-shaped shell;
      esp., the European Isocardia cor; -- called also heart
      cockle.

   Heart sickness, extreme depression of spirits.

   Heart and soul, with the utmost earnestness.

   Heart urchin (Zool.), any heartshaped, spatangoid sea
      urchin. See Spatangoid.

   Heart wheel, a form of cam, shaped like a heart. See Cam.


   In good heart, in good courage; in good hope.

   Out of heart, discouraged.

   Poor heart, an exclamation of pity.

   To break the heart of.
      (a) To bring to despair or hopeless grief; to cause to be
          utterly cast down by sorrow.
      (b) To bring almost to completion; to finish very nearly;
          -- said of anything undertaken; as, he has broken the
          heart of the task.

   To find in the heart, to be willing or disposed. "I could
      find in my heart to ask your pardon." --Sir P. Sidney.

   To have at heart, to desire (anything) earnestly.

   To have in the heart, to purpose; to design or intend to
      do.

   To have the heart in the mouth, to be much frightened.

   To lose heart, to become discouraged.

   To lose one's heart, to fall in love.

   To set the heart at rest, to put one's self at ease.

   To set the heart upon, to fix the desires on; to long for
      earnestly; to be very fond of.

   To take heart of grace, to take courage.

   To take to heart, to grieve over.

   To wear one's heart upon one's sleeve, to expose one's
      feelings or intentions; to be frank or impulsive.

   With all one's heart, With one's whole heart, very
      earnestly; fully; completely; devotedly.
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WordNet (r) 3.0 (2006):

heart and soul
    adv 1: with complete faith; "she was with him heart and soul"
           [syn: heart and soul, body and soul]
    n 1: the choicest or most essential or most vital part of some
         idea or experience; "the gist of the prosecutor's
         argument"; "the heart and soul of the Republican Party";
         "the nub of the story" [syn: kernel, substance, core,
         center, centre, essence, gist, heart, heart and
         soul, inwardness, marrow, meat, nub, pith,
         sum, nitty-gritty]

Moby Thesaurus II by Grady Ward, 1.0:

90 Moby Thesaurus words for "heart and soul":
   ad infinitum, all over, ardently, arduously, at all points,
   at full length, bec et ongles, breathlessly, committedly,
   cordially, decidedly, decisively, determinedly, devotedly,
   earnestly, effortfully, enthusiastically, every bit, every inch,
   every whit, excitedly, exuberantly, fervently, fervidly, firmly,
   fixedly, glowingly, hammer and tongs, hard, head and shoulders,
   heartily, heatedly, impassionedly, in all respects,
   in all seriousness, in earnest, in every respect, in extenso,
   in good earnest, industriously, inflexibly, inside and out,
   intensely, keenly, kindly, laboriously, like a bulldog,
   like a leech, manfully, neck deep, obstinately, on all counts,
   operosely, overall, passionately, perseveringly, persistently,
   purposefully, relentlessly, resolutely, resolvedly,
   root and branch, seriously, sincerely, singlemindedly, staunchly,
   steadfastly, steadily, strenuously, tenaciously, the hard way,
   through and through, throughout, to the brim, to the death,
   to the end, to the hilt, toilsomely, tooth and nail, unswervingly,
   unyieldingly, vigorously, warmly, wholeheartedly, with a will,
   with constancy, with effort, with total dedication, you name it,
   zealously