The Collaborative International Dictionary of English v.0.48:

Blank \Blank\, n.
   1. Any void space; a void space on paper, or in any written
      instrument; an interval void of consciousness, action,
      result, etc; a void.
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            I can not write a paper full, I used to do; and yet
            I will not forgive a blank of half an inch from you.
                                                  --Swift.
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            From this time there ensues a long blank in the
            history of French legislation.        --Hallam.
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            I was ill. I can't tell how long -- it was a blank.
                                                  --G. Eliot.
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   2. A lot by which nothing is gained; a ticket in a lottery on
      which no prize is indicated.
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            In Fortune's lottery lies
            A heap of blanks, like this, for one small prize.
                                                  --Dryden.
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   3. A paper unwritten; a paper without marks or characters a
      blank ballot; -- especially, a paper on which are to be
      inserted designated items of information, for which spaces
      are left vacant; a bland form.
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            The freemen signified their approbation by an
            inscribed vote, and their dissent by a blank.
                                                  --Palfrey.
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   4. A paper containing the substance of a legal instrument, as
      a deed, release, writ, or execution, with spaces left to
      be filled with names, date, descriptions, etc.
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   5. The point aimed at in a target, marked with a white spot;
      hence, the object to which anything is directed.
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            Let me still remain
            The true blank of thine eye.          --Shak.
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   6. Aim; shot; range. [Obs.]
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            I have stood . . . within the blank of his
            displeasure
            For my free speech.                   --Shak.
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   7. A kind of base silver money, first coined in England by
      Henry V., and worth about 8 pence; also, a French coin of
      the seventeenth century, worth about 4 pence. --Nares.
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   8. (Mech.) A piece of metal prepared to be made into
      something by a further operation, as a coin, screw, nuts.
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   9. (Dominoes) A piece or division of a piece, without spots;
      as, the "double blank"; the "six blank."
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   In blank, with an essential portion to be supplied by
      another; as, to make out a check in blank.
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The Collaborative International Dictionary of English v.0.48:

Blank \Blank\, a. [OE. blank, blonc, blaunc, blaunche, fr. F.
   blanc, fem. blanche, fr. OHG. blanch shining, bright, white,
   G. blank; akin to E. blink, cf. also AS. blanc white. ?98.
   See Blink, and cf. 1st Blanch.]
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   1. Of a white or pale color; without color.
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            To the blank moon
            Her office they prescribed.           --Milton.
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   2. Free from writing, printing, or marks; having an empty
      space to be filled in with some special writing; -- said
      of checks, official documents, etc.; as, blank paper; a
      blank check; a blank ballot.
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   3. Utterly confounded or discomfited.
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            Adam . . . astonied stood, and blank. --Milton.
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   4. Empty; void; without result; fruitless; as, a blank space;
      a blank day.
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   5. Lacking characteristics which give variety; as, a blank
      desert; a blank wall; destitute of interests, affections,
      hopes, etc.; as, to live a blank existence; destitute of
      sensations; as, blank unconsciousness.
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   6. Lacking animation and intelligence, or their associated
      characteristics, as expression of face, look, etc.;
      expressionless; vacant. "Blank and horror-stricken faces."
      --C. Kingsley.
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            The blank . . . glance of a half returned
            consciousness.                        --G. Eliot.
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   7. Absolute; downright; unmixed; as, blank terror.
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   Blank bar (Law), a plea put in to oblige the plaintiff in
      an action of trespass to assign the certain place where
      the trespass was committed; -- called also common bar.


   Blank cartridge, a cartridge containing no ball.

   Blank deed. See Deed.

   Blank door, or Blank window (Arch.), a depression in a
      wall of the size of a door or window, either for
      symmetrical effect, or for the more convenient insertion
      of a door or window at a future time, should it be needed.


   Blank indorsement (Law), an indorsement which omits the
      name of the person in whose favor it is made; it is
      usually made by simply writing the name of the indorser on
      the back of the bill.

   Blank line (Print.), a vacant space of the breadth of a
      line, on a printed page; a line of quadrats.

   Blank tire (Mech.), a tire without a flange.

   Blank tooling. See Blind tooling, under Blind.

   Blank verse. See under Verse.

   Blank wall, a wall in which there is no opening; a dead
      wall.
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The Collaborative International Dictionary of English v.0.48:

Blank \Blank\, v. t. [imp. & p. p. Blanked; p. pr. & vb. n.
   Blanking.] [Cf. 3d Blanch.]
   1. To make void; to annul. [Obs.] --Spenser.
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   2. To blanch; to make blank; to damp the spirits of; to
      dispirit or confuse. [Obs.]
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            Each opposite that blanks the face of joy. --Shak.
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WordNet (r) 3.0 (2006):

blank
    adj 1: (of a surface) not written or printed on; "blank pages";
           "fill in the blank spaces"; "a clean page"; "wide white
           margins" [syn: blank, clean, white]
    2: void of expression; "a blank stare" [syn: blank, vacuous]
    3: not charged with a bullet; "a blank cartridge"
    n 1: a blank character used to separate successive words in
         writing or printing; "he said the space is the most
         important character in the alphabet" [syn: space,
         blank]
    2: a blank gap or missing part [syn: lacuna, blank]
    3: a piece of material ready to be made into something
    4: a cartridge containing an explosive charge but no bullet
       [syn: blank, dummy, blank shell]
    v 1: keep the opposing (baseball) team from winning

Moby Thesaurus II by Grady Ward, 1.0:

248 Moby Thesaurus words for "blank":
   Olympian, absence, absolute, aloof, arid, awayness, backward, bald,
   bare, barren, bashful, bewildered, black, blah, bland, blankminded,
   bleached, blind, blind-alley, bloodless, box, calm, cecal,
   characterless, chasm, chilled, chilly, chirograph, choked,
   choked off, clean slate, clear, closed, cold, colorless, complete,
   confused, constrained, constricted, contracted, cool, dazed, dead,
   dead-end, deadpan, deprivation, detached, devoid, discomfited,
   disconcerted, discreet, dismal, distant, docket, document, dossier,
   downright, draggy, drearisome, dreary, dry, dryasdust, dull, dusty,
   effete, elephantine, emotionless, emptiness, empty, empty space,
   empty-headed, empty-minded, empty-pated, empty-skulled, etiolated,
   expressionless, fade, fatuous, featureless, file, fishy, flat,
   forbidding, form, frigid, frosty, glassy, guarded, heavy, helpless,
   ho-hum, hollow, holograph, icy, impassive, impersonal,
   inaccessible, inane, inanity, incogitant, inexcitable,
   inexpressive, insipid, instrument, introverted, jejune, lack,
   leaden, legal document, legal instrument, legal paper, lifeless,
   line, low-spirited, mindless, modest, naked, neverness, nil,
   nirvanic, nonexistence, nonoccurrence, nonplussed, nonpresence,
   nothing, nothingness, nowhereness, nude, null, null and void,
   oblivious, official document, offish, out-and-out, overlook,
   oversight, pale, pallid, paper, papers, parchment, passive,
   pedestrian, perfect, perplexed, personal file, plain, plodding,
   pointless, poker-faced, poky, ponderous, preterition, pure,
   quietistic, rattlebrained, rattleheaded, regular, relaxed, remote,
   removed, repressed, reserved, restrained, reticent, retiring, roll,
   scatterbrained, scrip, script, scroll, sheer, shrinking, shut,
   skip, slow, solemn, space, spiritless, squeezed shut, standoff,
   standoffish, stark, sterile, stiff, stodgy, straight-out,
   strangulated, stuffy, subdued, subtraction, superficial,
   suppressed, tabula rasa, tasteless, tedious, thoughtfree,
   thoughtless, tranquil, unadorned, unadulterated, unaffable,
   unapproachable, unarrayed, uncomplicated, uncongenial, undecked,
   undecorated, undemonstrative, undressed, unembellished,
   unexpansive, unexpressive, unfurbished, ungarnished, ungenial,
   unideaed, unintellectual, unlively, unmixed, unoccupied, unopen,
   unopened, unornamented, unqualified, unreasoning, unrelieved,
   unsophisticated, unthinking, untrimmed, unvarnished, unvented,
   unventilated, utter, vacant, vacuous, vacuum, vapid, void, want,
   white, with nothing inside, withdrawn, without content, wooden,
   writ, writing, zero



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

BLANK. A space left in writing to be filled, up with one or more words, in
order to make sense. 1. In what cases the ambiguity occasioned by blanks not
filled before execution of the writing may be explained 2. in what cases it
cannot be explained.
     2. - 1. When a blank is left in a written agreement which need not -
have been reduced to writing, and would have been equally binding whether
written or unwritten, it is presumed, in an action for the non-performance
of the contract, parol evidence might be admitted to explain the blank. And
where a written instrument, which was made professedly to record a fact, is
produced as evidence of that fact which it purports to record, and a blank
appears in a material part, the omission may be supplied by other proof. 1
Phil. Ev. 475 1 Wils. 215; 7 Verm. R. 522; 6 Verm. R. 411. Hence a blank
left in an award for a name, was allowed to be supplied by parol proof. 2
Dall. 180. But where a creditor signs a deed of composition leaving the
amount of his debt in blank, he binds himself to all existing debts. 1 B. &
A. 101; S. C. 2 Stark. R. 195.
     3. - 2. If a blank is left in a policy of insurance for the name of the
place of destination of a ship, it will avoid the policy. Molloy, b. 2, c.
7, s. 14; Park, Ins. 22; Wesk. Ins. 42. A paper signed and sealed in blank,
with verbal authority to. fill it up, which is afterwards done, is void,
unless afterwards delivered or acknowledged and adopted. 1 Yerg. 69, 149; 1
Hill, 267 2 N. & M. 125; 2 Brock. 64; 2 Dev. 379 1 Ham. 368; 6 Gill & John.
250; but see contra, 17 S. & R. 438. Lines ought to be drawn wherever there
are blanks, to prevent anything from being inserted afterwards. 2 Valin's
Comm. 151.
     4. When the filling up blanks after the execution of deeds and other
writings will vitiate them or not, see 3 Vin. Abr. 268; Moore, 547; Cro.
Eliz. 626; 1 Vent. 185; 2 Lev. 35; 2 Ch. R. 187; 1 Anst. 228; 5 Mass. 538; 4
Binn. 1; 9 Crancb, 28; Yelv. 96; 2 Show. 161; 1 Saund. Pl. & Ev. 77; 4 B. &
A. 672; Com. Dig. Fait, F 1; 4 @Bing. 123; 2 Hill. Ab. c. 25, Sec. 80; n. 33,
Sec. 54-and 72; 1 Ohio, R. 368; 4 Binn. R. 1; 6 Cowen, 118; Wright, 176.