"to cut roughly, cut with chopping blows," c.1200, from verb found in stem of Old English tohaccian "hack to pieces," from West Germanic *hakkon (cf. Old Frisian hackia "to chop or hack," Dutch hakken, Old High German hacchon, German hacken), from PIE *keg- "hook, tooth." Perhaps influenced by Old Norse höggva "to hack, hew" (cf. hacksaw). Slang sense of "cope with" (such as in can't hack it) is first recorded in American English 1955, with a sense of "get through by some effort," as a jungle (cf. phrase hack after "keep working away at" attested from late 14c.). Related: Hacked; hacking.
"illegally enter a computer system," by 1984; apparently a back-formation from hacker. Related: Hacked; hacking. Earlier verb senses were "to make commonplace" (1745), "make common by everyday use" (1590s), "use (a horse) for ordinary riding" (1560s), all from hack (n.2).
"to cough with a short, dry cough," 1802, perhaps from hack (v.1) on the notion of being done with difficulty, or else imitative.
"tool for chopping," early 14c., from hack (v.1); cf. Danish hakke "mattock," German Hacke "pickax, hatchet, hoe." Meaning "an act of cutting" is from 1836; figurative sense of "a try, an attempt" is first attested 1898.
"person hired to do routine work," c.1700, ultimately short for hackney "an ordinary horse" (c.1300), probably from place name Hackney, Middlesex (q.v.). Apparently nags were raised on the pastureland there in early medieval times. Extended sense of "horse for hire" (late 14c.) led naturally to "broken-down nag," and also "prostitute" (1570s) and "drudge" (1540s). Sense of "carriage for hire" (1704) led to modern slang for "taxicab." As an adjective, 1734, from the noun. Hack writer is first recorded 1826, though hackney writer is at least 50 years earlier. Hack-work is recorded from 1851.
To drive a taxi or bus: I worked in an office for years. Then I took to ''hacking'' (1931+)
[ultimately fr hackney, ''horse,'' fr Hackney, a village incorporated into London, fr Old English ''Haca's island'' or ''hook island''; presumably the horses were associated with the place]
[nearly all senses ultimately fr hack, ''cut, chop''; black and prison senses fr identification of prison guards with white persons in the pattern identical with that of the man; prison guards perhaps so called because they sometimes beat prisoners]
To gain unauthorized access to a computer system: hack into my site (1985+)