hash (n.1)

"a stew of meat cut into small pieces," 1660s, from hash (v.). Meaning "a mix, a mess" is from 1735.

hash (n.2)

short for hashish, 1959.

hash (v.)

1650s, "to hack, chop into small pieces," from French hacher "chop up" (14c.), from Old French hache "ax" (see hatchet). Hash browns (1926) is short for hashed browned potatoes (1886), with the -ed omitted, as in mash potatoes. The hash marks on a football field were so called by 1954, from their similarity to hash marks, armed forces slang for "service stripes on the sleeve of a military uniform" (1909), which supposedly were called that because they mark the number of years one has had free food (that is, hash (n.1)) from the Army; but perhaps there is a connection with the noun form of hatch (v.2).