monogram

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A design composed of one or more letters, typically the initials of a name, used as an identifying mark.
• transitive verb To mark with a design composed of one or more letters.

from The Century Dictionary.

• noun One character in writing; a mark or design formed or consisting of one letter.
• noun Two or more of the letters of a name or word, or of the initials of several names or words, so combined as to form or appear to form a single character.
• noun A picture drawn in lines without color; a sketch.

from the GNU version of the Collaborative International Dictionary of English.

• transitive verb To inscribe or ornament with a monogram.
• noun A character or cipher composed of two or more letters interwoven or combined so as to represent a name, or a part of it (usually the initials). Monograms are often used on seals, ornamental pins, rings, buttons, and by painters, engravers, etc., to distinguish their works.
• noun rare A picture in lines; a sketch.
• noun rare An arbitrary sign for a word.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun obsolete A picture drawn in line only, before the colour and/or shading is applied; an outline sketch.
• noun obsolete, rare A sentence consisting of only one line, or an epigram consisting of only one verse, of poetry.
• noun A design composed of one or more letters, often intertwined, used as an identifying mark of an individual or institution.
• verb transitive To mark something with a monogram.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a graphic symbol consisting of 2 or more letters combined (usually your initials); printed on stationery or embroidered on clothing