From The Collaborative International Dictionary of English v.0.48:

Public \Pub"lic\, a. [L. publicus, poblicus, fr. populus people:
   cf. F. public. See People.]
   1. Of or pertaining to the people; belonging to the people;
      relating to, or affecting, a nation, state, or community;
      -- opposed to private; as, the public treasury.
      [1913 Webster]

            To the public good
            Private respects must yield.          --Milton.
      [1913 Webster]

            He [Alexander Hamilton] touched the dead corpse of
            the public credit, and it sprung upon its feet. --D.
                                                  Webster.
      [1913 Webster]

   2. Open to the knowledge or view of all; general; common;
      notorious; as, public report; public scandal.
      [1913 Webster]

            Joseph, . . . not willing to make her a public
            example, was minded to put her away privily. --Matt.
                                                  i. 19.
      [1913 Webster]

   3. Open to common or general use; as, a public road; a public
      house. "The public street." --Shak.
      [1913 Webster]

   public act or public statute (Law), an act or statute
      affecting matters of public concern. Of such statutes the
      courts take judicial notice.

   Public credit. See under Credit.

   Public funds. See Fund, 3.

   Public house, an inn, or house of entertainment.

   Public law.
      (a) See International law, under International.
      (b) A public act or statute.

   Public nuisance. (Law) See under Nuisance.

   Public orator. (Eng. Universities) See Orator, 3.

   Public stores, military and naval stores, equipments, etc.
      

   Public works, all fixed works built by civil engineers for
      public use, as railways, docks, canals, etc.; but
      strictly, military and civil engineering works constructed
      at the public cost.
      [1913 Webster]

From The Collaborative International Dictionary of English v.0.48:

Public \Pub"lic\, n.
   1. The general body of mankind, or of a nation, state, or
      community; the people, indefinitely; as, the American
      public; also, a particular body or aggregation of people;
      as, an author's public.
      [1913 Webster]

            The public is more disposed to censure than to
            praise.                               --Addison.
      [1913 Webster]

   2. A public house; an inn. [Scot.] --Sir W. Scott.
      [1913 Webster]

   In public, openly; before an audience or the people at
      large; not in private or secrecy. "We are to speak in
      public." --Shak.
      [1913 Webster]

From WordNet (r) 2.0:

public
     adj 1: not private; open to or concerning the people as a whole;
            "the public good"; "public libraries"; "public funds";
            "public parks"; "a public scandal"; "public gardens";
            "performers and members of royal families are public
            figures" [ant: private]
     2: affecting the people or community as a whole; "community
        leaders"; "community interests"; "the public welfare"
     n 1: people in general considered as a whole; "he is a hero in
          the eyes of the public" [syn: populace, world]
     2: a body of people sharing some common interest; "the reading
        public"

From Moby Thesaurus II by Grady Ward, 1.0:

310 Moby Thesaurus words for "public":
   Babbittish, Everyman, John Doe, Philistine, Public, accessible,
   acknowledged, adherent, admitted, affirmed, alehouse, announced,
   apparent, appendage, associated, attendant, audience, available,
   bar, barrel house, barroom, beer garden, beer parlor, bistro,
   blatant, blind tiger, boardinghouse, body politic, bourgeois,
   bourgeoisie, broadcast, brought to notice, buff, business, buyers,
   cabaret, cafe, campy, carriage trade, catholic, cavaliere servente,
   celebrated, circulated, citizenry, citizens, civic, civil, clear,
   clear-cut, clientage, clientele, cocktail lounge, collective,
   collectivistic, common, common knowledge, common man,
   common property, commonalty, commonly known, commonplace,
   commonwealth, communal, communistic, community, community at large,
   commutual, conjoint, conjunct, conspicuous, constituency,
   consumers, cooperative, cortical, cosmopolitan, courtier,
   cultural community, current, custom, dangler, declared, demos,
   dependent, diffused, disciple, disreputable, disseminated,
   distributed, dive, dorm, dormitory, doss house, dramshop,
   drinking saloon, dwellers, eminent, epidermic, estate, everybody,
   everyman, everyone, everywoman, exomorphic, exposed, exterior,
   external, extrinsic, familiar, famous, fan, flagrant, fleabag,
   flophouse, flunky, folk, folks, follower, followers, following,
   free, fringe, general, general public, gentry, gin mill,
   government, governmental, groggery, grogshop, guest house,
   habitancy, hackneyed, hanger-on, henchman, high-camp, hoi polloi,
   homely, homespun, homme de cour, honky-tonk, hospice, hostel,
   hostelry, hotel, household, illustrious, in circulation, in common,
   in print, in public, in the open, infamous, influential,
   inhabitants, inn, international, joint, kitschy, known,
   linguistic community, local, lodging house, low-camp, made public,
   make public, manifest, market, masses, men, middle class,
   multitude, municipal, mutual, nation, national, nationality,
   nightclub, notable, noted, notorious, obvious, open, openly,
   ordinary, out, outer, outermost, outlying, outmost, outside,
   outstanding, outward, outward-facing, overt, parasite, partisan,
   patent, patronage, pension, people, people at large,
   people in general, peripheral, persons, plain, platitudinous,
   plebeian, plebeians, polity, pop, populace, popular, population,
   portion, posada, pothouse, proclaimed, projected, proletariat,
   prominent, propagated, proverbial, pub, public house, publicly,
   publish, published, purchasing public, pursuer, pursuivant,
   rank and file, rathskeller, reciprocal, renowned, reported,
   roadhouse, rooming house, roundabout, rumshop, rural market,
   saloon, saloon bar, satellite, sectary, sector, seeming, segment,
   shadow, shared, social, socialistic, societal, society, speakeasy,
   special-interest group, speech community, spread, state, stated,
   stooge, suburban market, successor, suite, superficial, supporter,
   supranational, surface, tagtail, tail, talked-about, talked-of,
   taproom, tavern, telecast, televised, the citizenry,
   the general public, the people, the populace, the population,
   the public, third estate, trade, trainbearer, trite, truistic,
   unconcealed, universal, universally admitted,
   universally recognized, unrestricted, unshrouded, urban,
   vernacular, viewable, visible, votary, ward heeler, well-kenned,
   well-known, well-recognized, well-understood, whole people,
   widely known, widespread, wine shop, world, worldwide, you and me,
   youth market

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

PUBLIC. By the term the public, is meant the whole body politic, or all the 
citizens of the state; sometimes it signifies the inhabitants of a 
particular place; as, the New York public. 
     2. A distinction has been made between the terms public and general, 
they are sometimes used as synonymous. The former term is applied strictly 
to that which concerns all the citizens and every member of the state; while 
the latter includes a lesser, though still a large portion of the community. 
Greenl. Ev. Sec. 128. 
     3. When the public interests and its rights conflict with those of an 
individual, the latter must yield. Co. Litt. 181. if, for example, a road is 
required for public convenience, and in its course it passes on the ground 
occupied by a house, the latter must be torn down, however valuable it may 
be to the owner. In such a case both law and justice require that the owner 
shall be fully indemnified. 
     4. This term is sometimes joined to other terms, to designate those 
things which have a relation to the public; as, a public officer, a public 
road, a public passage, a public house.