scribble

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

• intransitive verb To write (a note, for example) hurriedly without heed to legibility or style.
• intransitive verb To draw (a picture) hurriedly or carelessly.
• intransitive verb To write in a hurried careless way.
• intransitive verb To make meaningless marks, as with a pen or pencil.
• noun Careless hurried writing.
• noun Meaningless marks and lines.

from The Century Dictionary.

• To write with haste, or without care or regard to correctness or elegance: as, to scribble a letter or pamphlet.
• To cover or fill with careless or worthless writing, or unintelligible and entangled lines.
• To write without care or regard for correctness or elegance; scrawl; make unintelligible and entangled lines on paper or a slate for mere amusement, as a child does.
• noun Hurried or careless writing; a scrawl; hence, a shallow or trivial composition or article: as, a hasty scribble.
• noun [In the following quotation the word is used figuratively for a hurried, scrambling manner of walking, opposed to “a set pace,” as a scribble is to “a set copy.”
• To card or tease coarsely; pass, as cotton or wool, through a scribbler.

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

• transitive verb (Woolen Manuf.) To card coarsely; to run through the scribbling machine.
• intransitive verb To write without care, elegance, or value; to scrawl.
• transitive verb To write hastily or carelessly, without regard to correctness or elegance.
• transitive verb To fill or cover with careless or worthless writing.
• noun Hasty or careless writing; a writing of little value; a scrawl.

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

• verb To write or draw carelessly and in a hurry
• verb To doodle
• verb obsolete To card or tease (wool) coarsely; to run through a scribbler.
• noun Careless, hasty writing or drawing

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

• verb write carelessly
• noun an aimless drawing
• verb write down quickly without much attention to detail
• noun poor handwriting