The Collaborative International Dictionary of English v.0.48:

Common \Com"mon\, a. [Compar. Commoner; superl. Commonest.]
   [OE. commun, comon, OF. comun, F. commun, fr. L. communis;
   com- + munis ready to be of service; cf. Skr. mi to make
   fast, set up, build, Goth. gamains common, G. gemein, and E.
   mean low, common. Cf. Immunity, Commune, n. & v.]
   1. Belonging or relating equally, or similarly, to more than
      one; as, you and I have a common interest in the property.
      [1913 Webster]

            Though life and sense be common to men and brutes.
                                                  --Sir M. Hale.
      [1913 Webster]

   2. Belonging to or shared by, affecting or serving, all the
      members of a class, considered together; general; public;
      as, properties common to all plants; the common schools;
      the Book of Common Prayer.
      [1913 Webster]

            Such actions as the common good requireth. --Hooker.
      [1913 Webster]

            The common enemy of man.              --Shak.
      [1913 Webster]

   3. Often met with; usual; frequent; customary.
      [1913 Webster]

            Grief more than common grief.         --Shak.
      [1913 Webster]

   4. Not distinguished or exceptional; inconspicuous; ordinary;
      plebeian; -- often in a depreciatory sense.
      [1913 Webster]

            The honest, heart-felt enjoyment of common life.
                                                  --W. Irving.
      [1913 Webster]

            This fact was infamous
            And ill beseeming any common man,
            Much more a knight, a captain and a leader. --Shak.
      [1913 Webster]

            Above the vulgar flight of common souls. --A.
                                                  Murphy.
      [1913 Webster]

   5. Profane; polluted. [Obs.]
      [1913 Webster]

            What God hath cleansed, that call not thou common.
                                                  --Acts x. 15.
      [1913 Webster]

   6. Given to habits of lewdness; prostitute.
      [1913 Webster]

            A dame who herself was common.        --L'Estrange.
      [1913 Webster]

   Common bar (Law) Same as Blank bar, under Blank.

   Common barrator (Law), one who makes a business of
      instigating litigation.

   Common Bench, a name sometimes given to the English Court
      of Common Pleas.

   Common brawler (Law), one addicted to public brawling and
      quarreling. See Brawler.

   Common carrier (Law), one who undertakes the office of
      carrying (goods or persons) for hire. Such a carrier is
      bound to carry in all cases when he has accommodation, and
      when his fixed price is tendered, and he is liable for all
      losses and injuries to the goods, except those which
      happen in consequence of the act of God, or of the enemies
      of the country, or of the owner of the property himself.


   Common chord (Mus.), a chord consisting of the fundamental
      tone, with its third and fifth.

   Common council, the representative (legislative) body, or
      the lower branch of the representative body, of a city or
      other municipal corporation.

   Common crier, the crier of a town or city.

   Common divisor (Math.), a number or quantity that divides
      two or more numbers or quantities without a remainder; a
      common measure.

   Common gender (Gram.), the gender comprising words that may
      be of either the masculine or the feminine gender.

   Common law, a system of jurisprudence developing under the
      guidance of the courts so as to apply a consistent and
      reasonable rule to each litigated case. It may be
      superseded by statute, but unless superseded it controls.
      --Wharton.

   Note: It is by others defined as the unwritten law
         (especially of England), the law that receives its
         binding force from immemorial usage and universal
         reception, as ascertained and expressed in the
         judgments of the courts. This term is often used in
         contradistinction from statute law. Many use it to
         designate a law common to the whole country. It is also
         used to designate the whole body of English (or other)
         law, as distinguished from its subdivisions, local,
         civil, admiralty, equity, etc. See Law.

   Common lawyer, one versed in common law.

   Common lewdness (Law), the habitual performance of lewd
      acts in public.

   Common multiple (Arith.) See under Multiple.

   Common noun (Gram.), the name of any one of a class of
      objects, as distinguished from a proper noun (the name of
      a particular person or thing).

   Common nuisance (Law), that which is deleterious to the
      health or comfort or sense of decency of the community at
      large.

   Common pleas, one of the three superior courts of common
      law at Westminster, presided over by a chief justice and
      four puisne judges. Its jurisdiction is confined to civil
      matters. Courts bearing this title exist in several of the
      United States, having, however, in some cases, both civil
      and criminal jurisdiction extending over the whole State.
      In other States the jurisdiction of the common pleas is
      limited to a county, and it is sometimes called a county
      court. Its powers are generally defined by statute.

   Common prayer, the liturgy of the Church of England, or of
      the Protestant Episcopal church of the United States,
      which all its clergy are enjoined to use. It is contained
      in the Book of Common Prayer.

   Common school, a school maintained at the public expense,
      and open to all.

   Common scold (Law), a woman addicted to scolding
      indiscriminately, in public.

   Common seal, a seal adopted and used by a corporation.

   Common sense.
      (a) A supposed sense which was held to be the common bond
          of all the others. [Obs.] --Trench.
      (b) Sound judgment. See under Sense.

   Common time (Mus.), that variety of time in which the
      measure consists of two or of four equal portions.

   In common, equally with another, or with others; owned,
      shared, or used, in community with others; affecting or
      affected equally.

   Out of the common, uncommon; extraordinary.

   Tenant in common, one holding real or personal property in
      common with others, having distinct but undivided
      interests. See Joint tenant, under Joint.

   To make common cause with, to join or ally one's self with.

   Syn: General; public; popular; national; universal; frequent;
        ordinary; customary; usual; familiar; habitual; vulgar;
        mean; trite; stale; threadbare; commonplace. See
        Mutual, Ordinary, General.
        [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Common sense \Com"mon sense"\
   See Common sense, under Sense.

The Collaborative International Dictionary of English v.0.48:

Sense \Sense\, n. [L. sensus, from sentire, sensum, to perceive,
   to feel, from the same root as E. send; cf. OHG. sin sense,
   mind, sinnan to go, to journey, G. sinnen to meditate, to
   think: cf. F. sens. For the change of meaning cf. See, v.
   t. See Send, and cf. Assent, Consent, Scent, v. t.,
   Sentence, Sentient.]
   1. (Physiol.) A faculty, possessed by animals, of perceiving
      external objects by means of impressions made upon certain
      organs (sensory or sense organs) of the body, or of
      perceiving changes in the condition of the body; as, the
      senses of sight, smell, hearing, taste, and touch. See
      Muscular sense, under Muscular, and Temperature
      sense, under Temperature.
      [1913 Webster]

            Let fancy still my sense in Lethe steep. --Shak.
      [1913 Webster]

            What surmounts the reach
            Of human sense I shall delineate.     --Milton.
      [1913 Webster]

            The traitor Sense recalls
            The soaring soul from rest.           --Keble.
      [1913 Webster]

   2. Perception by the sensory organs of the body; sensation;
      sensibility; feeling.
      [1913 Webster]

            In a living creature, though never so great, the
            sense and the affects of any one part of the body
            instantly make a transcursion through the whole.
                                                  --Bacon.
      [1913 Webster]

   3. Perception through the intellect; apprehension;
      recognition; understanding; discernment; appreciation.
      [1913 Webster]

            This Basilius, having the quick sense of a lover.
                                                  --Sir P.
                                                  Sidney.
      [1913 Webster]

            High disdain from sense of injured merit. --Milton.
      [1913 Webster]

   4. Sound perception and reasoning; correct judgment; good
      mental capacity; understanding; also, that which is sound,
      true, or reasonable; rational meaning. "He speaks sense."
      --Shak.
      [1913 Webster]

            He raves; his words are loose
            As heaps of sand, and scattering wide from sense.
                                                  --Dryden.
      [1913 Webster]

   5. That which is felt or is held as a sentiment, view, or
      opinion; judgment; notion; opinion.
      [1913 Webster]

            I speak my private but impartial sense
            With freedom.                         --Roscommon.
      [1913 Webster]

            The municipal council of the city had ceased to
            speak the sense of the citizens.      --Macaulay.
      [1913 Webster]

   6. Meaning; import; signification; as, the true sense of
      words or phrases; the sense of a remark.
      [1913 Webster]

            So they read in the book in the law of God
            distinctly, and gave the sense.       --Neh. viii.
                                                  8.
      [1913 Webster]

            I think 't was in another sense.      --Shak.
      [1913 Webster]

   7. Moral perception or appreciation.
      [1913 Webster]

            Some are so hardened in wickedness as to have no
            sense of the most friendly offices.   --L' Estrange.
      [1913 Webster]

   8. (Geom.) One of two opposite directions in which a line,
      surface, or volume, may be supposed to be described by the
      motion of a point, line, or surface.
      [1913 Webster]

   Common sense, according to Sir W. Hamilton:
      (a) "The complement of those cognitions or convictions
          which we receive from nature, which all men possess in
          common, and by which they test the truth of knowledge
          and the morality of actions."
      (b) "The faculty of first principles." These two are the
          philosophical significations.
      (c) "Such ordinary complement of intelligence, that,if a
          person be deficient therein, he is accounted mad or
          foolish."
      (d) When the substantive is emphasized: "Native practical
          intelligence, natural prudence, mother wit, tact in
          behavior, acuteness in the observation of character,
          in contrast to habits of acquired learning or of
          speculation."

   Moral sense. See under Moral,
      (a) .

   The inner sense, or The internal sense, capacity of the
      mind to be aware of its own states; consciousness;
      reflection. "This source of ideas every man has wholly in
      himself, and though it be not sense, as having nothing to
      do with external objects, yet it is very like it, and
      might properly enough be called internal sense." --Locke.

   Sense capsule (Anat.), one of the cartilaginous or bony
      cavities which inclose, more or less completely, the
      organs of smell, sight, and hearing.

   Sense organ (Physiol.), a specially irritable mechanism by
      which some one natural force or form of energy is enabled
      to excite sensory nerves; as the eye, ear, an end bulb or
      tactile corpuscle, etc.

   Sense organule (Anat.), one of the modified epithelial
      cells in or near which the fibers of the sensory nerves
      terminate.
      [1913 Webster]

   Syn: Understanding; reason.

   Usage: Sense, Understanding, Reason. Some philosophers
          have given a technical signification to these terms,
          which may here be stated. Sense is the mind's acting
          in the direct cognition either of material objects or
          of its own mental states. In the first case it is
          called the outer, in the second the inner, sense.
          Understanding is the logical faculty, i. e., the power
          of apprehending under general conceptions, or the
          power of classifying, arranging, and making
          deductions. Reason is the power of apprehending those
          first or fundamental truths or principles which are
          the conditions of all real and scientific knowledge,
          and which control the mind in all its processes of
          investigation and deduction. These distinctions are
          given, not as established, but simply because they
          often occur in writers of the present day.
          [1913 Webster]

WordNet (r) 3.0 (2006):

common sense
    n 1: sound practical judgment; "Common sense is not so common";
         "he hasn't got the sense God gave little green apples";
         "fortunately she had the good sense to run away" [syn:
         common sense, good sense, gumption, horse sense,
         sense, mother wit]

Moby Thesaurus II by Grady Ward, 1.0:

37 Moby Thesaurus words for "common sense":
   admissibility, balance, cool head, coolheadedness, coolness,
   due sense of, good sense, gumption, horse sense, judgment,
   justifiability, justness, level head, levelheadedness, logic,
   logicality, logicalness, plain sense, plausibility, practical mind,
   practical wisdom, practicality, rationality, reason, reasonability,
   reasonableness, saneness, sanity, sense, sensibleness,
   sober-mindedness, soberness, sobriety, sound sense, soundness,
   sweet reason, wisdom



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

COMMON SENSE, med. jur. When a person possesses those perceptions,
associations and judgments, in relation to persons and things, which agree
with those of the generality of mankind, he is said to possess common sense.
On the contrary, when a particular individual differs from the generality of
persons in these respects, he is said not to have common sense, or not to be
in his senses. 1 Chit. Med. Jur. 334.