The Collaborative International Dictionary of English v.0.48:

Form \Form\ (f[=o]rm; in senses 8 & 9, often f[=o]rm in
   England), n. [OE. & F. forme, fr. L. forma; cf. Skr.
   dhariman. Cf. Firm.]
   1. The shape and structure of anything, as distinguished from
      the material of which it is composed; particular
      disposition or arrangement of matter, giving it
      individuality or distinctive character; configuration;
      figure; external appearance.
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            The form of his visage was changed.   --Dan. iii.
                                                  19.
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            And woven close close, both matter, form, and style.
                                                  --Milton.
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   2. Constitution; mode of construction, organization, etc.;
      system; as, a republican form of government.
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   3. Established method of expression or practice; fixed way of
      proceeding; conventional or stated scheme; formula; as, a
      form of prayer.
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            Those whom form of laws
            Condemned to die.                     --Dryden.
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   4. Show without substance; empty, outside appearance; vain,
      trivial, or conventional ceremony; conventionality;
      formality; as, a matter of mere form.
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            Though well we may not pass upon his life
            Without the form of justice.          --Shak.
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   5. Orderly arrangement; shapeliness; also, comeliness;
      elegance; beauty.
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            The earth was without form and void.  --Gen. i. 2.
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            He hath no form nor comeliness.       --Is. liii. 2.
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   6. A shape; an image; a phantom.
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   7. That by which shape is given or determined; mold; pattern;
      model.
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   8. A long seat; a bench; hence, a rank of students in a
      school; a class; also, a class or rank in society. "Ladies
      of a high form." --Bp. Burnet.
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   9. The seat or bed of a hare.
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            As in a form sitteth a weary hare.    --Chaucer.
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   10. (Print.) The type or other matter from which an
       impression is to be taken, arranged and secured in a
       chase.
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   11. (Fine Arts) The boundary line of a material object. In
       (painting), more generally, the human body.
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   12. (Gram.) The particular shape or structure of a word or
       part of speech; as, participial forms; verbal forms.
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   13. (Crystallog.) The combination of planes included under a
       general crystallographic symbol. It is not necessarily a
       closed solid.
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   14. (Metaph.) That assemblage or disposition of qualities
       which makes a conception, or that internal constitution
       which makes an existing thing to be what it is; -- called
       essential or substantial form, and contradistinguished
       from matter; hence, active or formative nature; law of
       being or activity; subjectively viewed, an idea;
       objectively, a law.
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   15. Mode of acting or manifestation to the senses, or the
       intellect; as, water assumes the form of ice or snow. In
       modern usage, the elements of a conception furnished by
       the mind's own activity, as contrasted with its object or
       condition, which is called the matter; subjectively, a
       mode of apprehension or belief conceived as dependent on
       the constitution of the mind; objectively, universal and
       necessary accompaniments or elements of every object
       known or thought of.
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   16. (Biol.) The peculiar characteristics of an organism as a
       type of others; also, the structure of the parts of an
       animal or plant.
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   Good form or Bad form, the general appearance, condition
      or action, originally of horses, afterwards of persons;
      as, the members of a boat crew are said to be in good form
      when they pull together uniformly. The phrases are further
      used colloquially in description of conduct or manners in
      society; as, it is not good form to smoke in the presence
      of a lady.
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WordNet (r) 3.0 (2006):

good form
    n 1: behavior that conforms to social conventions of the time;
         "it is not good form to brag about winning"

Moby Thesaurus II by Grady Ward, 1.0:

46 Moby Thesaurus words for "good form":
   amenities, bienseance, civilities, civility, comity, conformity,
   convenance, convention, conventional usage, conventionalism,
   conventionality, correctness, courtliness, custom, decencies,
   decency, decorousness, decorum, diplomatic code, elegance,
   elegancies, etiquette, exquisite manners, form, formalities,
   formality, good manners, manners, mores, natural politeness,
   point of etiquette, politeness, politesse, proprieties, propriety,
   protocol, punctilio, quiet good manners, rules of conduct,
   seemliness, social code, social conduct, social convention,
   social graces, social procedures, social usage