| Word | Reading | Meaning |
| 強硬 | きょうこう | firm, vigorous, unbending, unyielding, strong, stubborn |
| 硬派 | こうは | tough elements, hard-liners, stalwart(s) |
| 硬直 | こうちょく | stiffening, rigidity, rigor, stiffness, ossification, petrification |
| 硬貨 | こうか | coin |
| 肝硬変 | かんこうへん | cirrhosis of the liver |
| 硬さ | かたさ | firmness, hardness, stiffness, honesty |
| 動脈硬化 | どうみゃくこうか | arteriosclerosis, hardening of the arteries |
| 硬式 | こうしき | hardball (tennis, baseball) |
| 硬軟 | こうなん | hardness |
| 硬い | かたい | hard, solid, tough; stiff, tight, wooden, unpolished (e.g. writing); strong, firm (not viscous or easily moved); safe, steady, honest, steadfast; obstinate, stubborn; bookish, formal, stuffy |