Translation guide
The English verb "harden" covers physical stiffening, emotional toughening, and figurative intensification. Japanese uses different verbs depending on what is hardening and whether the change is natural, intentional, or metaphorical.
Describing a substance or object that becomes firm, solid, or rigid, often through cooling, drying, or chemical change.
General intransitive verb for something solidifying or hardening naturally. Used for concrete, jelly, glue, etc.
Please wait until the cement hardens.
The jelly hardens in the refrigerator.
Transitive verb: to harden something intentionally, like shaping and setting hair, or compacting soil.
I hardened my hair with hairspray.
Technical or formal term for hardening, often used in science, engineering, or medical contexts (e.g., resin hardening, arteriosclerosis).
This resin hardens with heat.
Describing a person who becomes less sensitive, more resilient, or emotionally cold, often due to experience.
Literally "turn one's heart into a demon." Means to harden one's heart, usually to do something difficult but necessary.
I hardened my heart and scolded my child.
To kill one's emotions; to suppress feelings and become emotionally hardened.
To become cold-hearted or ruthless. Implies a permanent or severe change in character.
He hardened after gaining power and became ruthless.
Describing a strengthening of resolve, attitude, or stance, often in the face of opposition.
To firm up one's resolve; to make a firm decision. Very common for personal determination.
He hardened his resolve to study abroad.
To harden one's attitude; to take a tougher stance. Often used in negotiations or politics.
To become hawkish or hardline. Used for political or ideological hardening.
Opinions within the party hardened.
Treating a material to make it harder or more durable, often through industrial processes.
Direct translations like 「心が固まる」 are not idiomatic and may sound like a physical description. Use set phrases like 「心を鬼にする」 or 「感情を殺す」 instead.
固まる is intransitive (something hardens by itself), while 固める is transitive (someone hardens something). Choose based on whether there is an agent causing the hardening.
He hardened his emotions and spoke matter-of-factly.
The government hardened its stance in the negotiations.
Apply a treatment to harden the surface of the gear.