means To write hastily or carelessly, producing marks that are messy, irregular, and often barely legible.

from English, from the late 1500s, with murky roots — possibly a blend of 'sprawl' (to spread out untidily) and 'crawl' (to move in a slow, uneven way). The connection feels right: a scrawl is handwriting that sprawls across the page and crawls past legibility, though the precise origin stays uncertain.