Hard
Hard or Hardness may refer to:
- Hardness, resistance of physical materials to change under force
- Hard water, water with a high mineral content
- NP-hard, a term used in Computational complexity theory
- Hard, Austria, a town in Austria
- Hard (Zürich), a quarter in Zürich
- Hard (tennis), a type of tennis court
- Hard (music festival), concerts and live events
- Hard, or hard-on, a slang term for an erection
- Hard (nautical), a firm or paved beach or slope convenient for hauling vessels out of the water
- Hayward Area Recreation and Park District, abbreviated H.A.R.D.
- Music