scrabble v.

1580s (intransitive), "make one's way by clambering, etc., struggle or wriggle along," also "strive with others or jostle and grasp rudely for a share or for mastery;" a word of obscure origin, perhaps a nasalized variant of scrabble (v.) "to struggle; to scrape quickly." OED points to dialectal scramb "pull together with the hands," a variant of scramp, which is probably a nasalized form of scrape.

Mrs. Goddard was the mistress of a school, ... a real, honest, old fashioned boarding-school, where a reasonable quantity of accomplishments were sold at a reasonable price, and where girls might be sent to be out of the way, and scramble themselves into a little education, without any danger of coming back prodigies. [Jane Austen, "Emma"]

The transitive sense of "to stir or toss together randomly, cause to move confusedly" is from 1822. The transitive sense, in reference to radio signals, telephone voices, etc., "to make unintelligible," is attested from 1927, hence generally "to jumble, muddle." In U.S. football, in reference to a quarterback avoiding tacklers, by 1964. Related: Scrambled; scrambling. Scrambled eggs, broken into a pan, mixed with butter, salt, pepper, etc., and cooked slowly,is by 1843.

mid-15c., scriblen, "to write (something) quickly and carelessly, without regard to correctness or elegance," from Medieval Latin scribillare, diminutive of Latin scribere "to write" (from PIE root *skribh- "to cut"). Or perhaps a native formation from Middle English scriben "to write" (see scribe (v.)) + diminutive suffix -el (3). Classical Latin had conscribillare. The sense of "make unintelligible tangled lines on paper out of idleness or for amusement" is modern. Related: Scribbled; scribbling.

The noun, "hurried or careless writing," is 1570s, from the verb. The 19c. writers enjoyed the sound of scribble, based on their many elaborations of it in describing one another: scribblage, scribblative, scribblatory, scribbleable, scribbledom, but the 17c., beat them to two of the best: scribblement and scribble-wit.