Perhaps from crawl, influenced by scrawl 'to lie carelessly' (14-19 centuries)
to write in a careless and untidy way, so that your words are not easy to read [↪ scribble]:
He scrawled his name at the bottom.
WORD FOCUS: write WORD FOCUS: write quickly:jot down, dash off in a way that is difficult to read:scribble, scrawl write information on an official form:fill in/fill out write a word correctly:spell start to write:put pen to paper ➔ See alsowrite
Definition from the Longman Dictionary of Contemporary English Advanced Learner's Dictionary.