What does HACK mean?

noun

1. one who works hard at boring tasks
2. a politician who belongs to a small clique that controls a political party for private rather than public ends
3. a mediocre and disdained writer
4. a tool (as a hoe or pick or mattock) used for breaking up the surface of the soil
5. a car driven by a person whose job is to take passengers where they want to go in exchange for money
6. an old or over-worked horse
7. a horse kept for hire
8. a saddle horse used for transportation rather than sport etc.