Translation guide
The emission or transmission of energy as waves or particles, often referring to nuclear radiation, electromagnetic radiation, or heat radiation. In Japanese, the most common word is 放射線 (ほうしゃせん) for nuclear/ionizing radiation, but context matters: light/heat radiation uses 放射 (ほうしゃ), and electromagnetic waves are 電磁波 (でんじは).
The most common meaning: harmful or penetrating rays from radioactive materials, nuclear reactions, or medical imaging.
The standard term for nuclear radiation, including alpha, beta, gamma, and X-rays. Used in medical, scientific, and everyday contexts.
I'm receiving radiation therapy.
Measure the radiation dose.
Refers to 'radioactivity' – the property of emitting radiation. Often used in news about contamination or leaks. Not a direct synonym for 'radiation' itself, but closely related.
Strictly means 'radioactivity', not the rays themselves. 放射線 is the rays; 放射能 is the ability to emit them.
I'm worried about the radiation leak.
Exposure to radiation (usually harmful). Used in medical or accident contexts.
I was exposed to radiation.
Radiation in the physics sense: energy traveling through space as electromagnetic waves.
The general term for electromagnetic waves, including radio, light, X-rays. Used in physics and engineering.
Investigate the effects of electromagnetic radiation.
The act or process of radiating (emitting energy). Often used in compounds like 熱放射 (heat radiation) or 放射エネルギー (radiant energy).
Infrared radiation emitted by hot objects; warmth felt from a fire or heater.
Abstract or broad use: the process of radiating waves or particles.
放射線 (ほうしゃせん) = the rays/particles themselves (radiation). 放射能 (ほうしゃのう) = radioactivity (the ability to emit). 放射 (ほうしゃ) = the act/process of radiating. In news about nuclear accidents, 放射線量 (radiation dose) and 放射能漏れ (radioactivity leak) are common.
For sunlight, radio waves, or heat, 放射線 sounds like nuclear radiation. Use 電磁波 (electromagnetic waves) or 熱放射 (heat radiation) instead.
The radiation from the sun includes visible light and ultraviolet rays.
After the accident, they checked the radiation levels.
radiant energy from the sun
輻射熱で部屋が暖かい。
The room is warm from radiant heat.