The Collaborative International Dictionary of English v.0.48:
Letter \Let"ter\, n. [OE. lettre, F. lettre, OF. letre, fr. L.
littera, litera, a letter; pl., an epistle, a writing,
literature, fr. linere, litum, to besmear, to spread or rub
over; because one of the earliest modes of writing was by
graving the characters upon tablets smeared over or covered
with wax. --Pliny, xiii. 11. See Liniment, and cf.
Literal.]
1. A mark or character used as the representative of a sound,
or of an articulation of the human organs of speech; a
first element of written language.
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And a superscription also was written over him in
letters of Greek, and Latin, and Hebrew. --Luke
xxiii. 38.
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2. A written or printed communication; a message expressed in
intelligible characters on something adapted to
conveyance, as paper, parchment, etc.; an epistle.
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The style of letters ought to be free, easy, and
natural. --Walsh.
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3. A writing; an inscription. [Obs.]
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None could expound what this letter meant.
--Chaucer.
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4. Verbal expression; literal statement or meaning; exact
signification or requirement.
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We must observe the letter of the law, without doing
violence to the reason of the law and the intention
of the lawgiver. --Jer. Taylor.
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I broke the letter of it to keep the sense.
--Tennyson.
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5. (Print.) A single type; type, collectively; a style of
type.
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Under these buildings . . . was the king's printing
house, and that famous letter so much esteemed.
--Evelyn.
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6. pl. Learning; erudition; as, a man of letters.
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7. pl. A letter; an epistle. [Obs.] --Chaucer.
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8. (Teleg.) A telegram longer than an ordinary message sent
at rates lower than the standard message rate in
consideration of its being sent and delivered subject to
priority in service of regular messages. Such telegrams
are called by the Western Union Company day letters, or
night letters according to the time of sending, and by
The Postal Telegraph Company day lettergrams, or night
lettergrams.
[Webster 1913 Suppl.]
Dead letter, Drop letter, etc. See under Dead, Drop,
etc.
Letter book, a book in which copies of letters are kept.
Letter box, a box for the reception of letters to be mailed
or delivered.
Letter carrier, a person who carries letters; a postman;
specif., an officer of the post office who carries letters
to the persons to whom they are addressed, and collects
letters to be mailed.
Letter cutter, one who engraves letters or letter punches.
Letter lock, a lock that can not be opened when fastened,
unless certain movable lettered rings or disks forming a
part of it are in such a position (indicated by a
particular combination of the letters) as to permit the
bolt to be withdrawn.
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A strange lock that opens with AMEN. --Beau. & Fl.
Letter paper, paper for writing letters on; especially, a
size of paper intermediate between note paper and
foolscap. See Paper.
Letter punch, a steel punch with a letter engraved on the
end, used in making the matrices for type.
Letters of administration (Law), the instrument by which an
administrator or administratrix is authorized to
administer the goods and estate of a deceased person.
Letter of attorney, Letter of credit, etc. See under
Attorney, Credit, etc.
Letter of license, a paper by which creditors extend a
debtor's time for paying his debts.
Letters close or Letters clause (Eng. Law.), letters or
writs directed to particular persons for particular
purposes, and hence closed or sealed on the outside; --
distinguished from letters patent. --Burrill.
Letters of orders (Eccl.), a document duly signed and
sealed, by which a bishop makes it known that he has
regularly ordained a certain person as priest, deacon,
etc.
Letters patent, Letters overt, or Letters open (Eng.
Law), a writing executed and sealed, by which power and
authority are granted to a person to do some act, or enjoy
some right; as, letters patent under the seal of England.
The common commercial patent is a derivative form of
such a right.
Letter-sheet envelope, a stamped sheet of letter paper
issued by the government, prepared to be folded and sealed
for transmission by mail without an envelope.
Letters testamentary (Law), an instrument granted by the
proper officer to an executor after probate of a will,
authorizing him to act as executor.
Letter writer.
(a) One who writes letters.
(b) A machine for copying letters.
(c) A book giving directions and forms for the writing of
letters.
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Bouvier's Law Dictionary, Revised 6th Ed (1856):
LETTER BOOK, commerce. A book containing the copies of letters written by a
merchant or trader to his correspondents.
2. After notice to the plaintiff to produce a letter which he admitted
to have received from the defendant, it was held that an entry by a deceased
clerk, in a letter book professing to be a copy of a letter from the
defendant to the plaintiff of the same date, was admissible evidence of the
contents, proof having been given, that according to the course of business,
letters of business written by the plaintiff were copied by this clerk and
then sent off by the post. 3 Campb. R. 305. Vide 1 Stark Ev. 356; Bouv.
Inst. n. 3139.