let·ter 
(lĕtər)
(lĕtər)n.
1.
a. A written symbol or character representing a speech sound and being a component of an alphabet.
b. A written symbol or character used in the graphemic representation of a word, such as the h in Thames. See Note at Thames.
2. A written or printed communication directed to a person or organization.
3. often letters A certified document granting rights to its bearer.
4. Literal meaning: had to adhere to the letter of the law.
5. letters (used with a sing. verb)
a. Literary culture; belles-lettres.
b. Learning or knowledge, especially of literature.
c. Literature or writing as a profession.
6. Printing
a. A piece of type that prints a single character.
b. A specific style of type.
c. The characters in one style of type.
7. An emblem in the shape of the initial of a school awarded for outstanding performance, especially in varsity athletics.
v. let·tered, let·ter·ing, let·ters
v.tr.
1. To write letters on: lettered the paper.
2. To write in letters: lettered our name on the mailbox.
v.intr.
Idiom: 1. To write or form letters.
2. To earn a school letter, as for outstanding athletic achievement: She lettered in three collegiate sports.
to the letter
To the last detail; exactly: followed instructions to the letter.
[Middle English, from Old French lettre, from Latin littera, perhaps from Etruscan, from Greek diphtherā, hide, leather, writing surface.]
letter·er n.
Synonyms: letter, epistle, memorandum, missive, note
These nouns denote a written communication directed to another: received a letter of complaint; the Epistles of the New Testament; a memorandum outlining the attendance policy; a missive of condolence; a thank-you note.
These nouns denote a written communication directed to another: received a letter of complaint; the Epistles of the New Testament; a memorandum outlining the attendance policy; a missive of condolence; a thank-you note.