The Collaborative International Dictionary of English v.0.48:

frank \frank\ (fr[a^][ng]k), v. t. [imp. & p. p. franked
   (fr[a^][ng]kt); p. pr. & vb. n. franking.]
   1. To send by public conveyance free of expense. --Dickens.
      [1913 Webster]

   2. To extempt from charge for postage, as a letter, package,
      or packet, etc.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Frank \Frank\, n. [See Frank, a.]
   The privilege of sending letters or other mail matter, free
   of postage, or without charge; also, the sign, mark, or
   signature denoting that a letter or other mail matter is to
   go free of postage. Called also the franking privilege.
   [1913 Webster +PJC]

         I have said so much, that, if I had not a frank, I must
         burn my letter and begin again.          --Cowper.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Frank \Frank\, n. [OF. franc.]
   A pigsty. [Obs.]
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Frank \Frank\, v. t.
   To shut up in a frank or sty; to pen up; hence, to cram; to
   fatten. [Obs.] --Shak.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Frank \Frank\, n. (Zool.)
   The common heron; -- so called from its note. [Prov. Eng.]
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

frank \frank\ (fr[a^][ng]k), a. [Compar. franker
   (fr[a^][ng]k"[~e]r); superl. frankest.] [F. franc free,
   frank, L. Francus a Frank, fr. OHG. Franko the name of a
   Germanic people on the Rhine, who afterward founded the
   French monarchy; cf. AS. franca javelin, Icel. frakka. Cf.
   Franc, French, a., Franchise, n.]
   1. Unbounded by restrictions, limitations, etc.; free. [R.]
      "It is of frank gift." --Spenser.
      [1913 Webster]

   2. Free in uttering one's real sentiments; not reserved;
      using no disguise; candid; ingenuous; as, a frank nature,
      conversation, manner, etc.
      [1913 Webster]

   3. Liberal; generous; profuse. [Obs.]
      [1913 Webster]

            Frank of civilities that cost them nothing.
                                                  --L'Estrange.
      [1913 Webster]

   4. Unrestrained; loose; licentious; -- used in a bad sense.
      --Spenser.

   Syn: Ingenuous; candid; artless; plain; open; unreserved;
        undisguised; sincere. See Candid, Ingenuous.
        [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Frank \Frank\, n. [Cf. F. franc. See Frank, a.]
   1. (Ethnol.) A member of one of the German tribes that in the
      fifth century overran and conquered Gaul, and established
      the kingdom of France.
      [1913 Webster]

   2. A native or inhabitant of Western Europe; a European; -- a
      term used in the Levant.
      [1913 Webster]

   3. A French coin. See Franc.
      [1913 Webster]

WordNet (r) 3.0 (2006):

frank
    adj 1: characterized by directness in manner or speech; without
           subtlety or evasion; "blunt talking and straight
           shooting"; "a blunt New England farmer"; "I gave them my
           candid opinion"; "forthright criticism"; "a forthright
           approach to the problem"; "tell me what you think--and
           you may just as well be frank"; "it is possible to be
           outspoken without being rude"; "plainspoken and to the
           point"; "a point-blank accusation" [syn: blunt,
           candid, forthright, frank, free-spoken,
           outspoken, plainspoken, point-blank, straight-
           from-the-shoulder]
    2: clearly manifest; evident; "frank enjoyment"
    n 1: a member of the ancient Germanic peoples who spread from
         the Rhine into the Roman Empire in the 4th century
    2: a smooth-textured sausage of minced beef or pork usually
       smoked; often served on a bread roll [syn: frank,
       frankfurter, hotdog, hot dog, dog, wiener,
       wienerwurst, weenie]
    v 1: stamp with a postmark to indicate date and time of mailing
         [syn: postmark, frank]
    2: exempt by means of an official pass or letter, as from
       customs or other checks

The Free On-line Dictionary of Computing (19 January 2023):

FRANK

   ["Using BINS for Interprocess Communication", P.C.J. Graham,
   SIGPLAN Notices 20(2):32-41 (Feb 1985)].

   (1995-01-13)