How to say "radiation" in Japanese
Choosing the right word
- 放射ほうしゃnoun, suru verb, transitive verbThe most direct word for 'radiation' as energy or particles emitted from a source, as in physics contexts. Use this when talking about radiation itself rather than the act of releasing or directing it.
- 放出ほうしゅつnoun, suru verb, transitive verb, intransitive verbCovers 'radiation' in the sense of an emission or release from a source. The emphasis falls on the act of letting something out, so it suits contexts of discharging energy or matter rather than the radiation as a phenomenon.
- 照射しょうしゃnoun, suru verb, transitive verb, intransitive verbRefers to irradiation: radiation directed at, or beamed onto, a target. Choose this when radiation is applied to something, such as shining or beaming energy onto an object, rather than when discussing radiation in general.
- 発散はっさんnoun, suru verb, transitive verb, intransitive verbMeans emanation or diffusion — something spreading outward from a source. As 'radiation' it is a more marginal choice, fitting the spreading or diffusing sense; for ordinary physical radiation, 放射 is usually the word you want.
- 発光はっこうnoun, suru verb, intransitive verbStrictly about light: the emission or radiation of light, or luminescence. It is not a general word for 'radiation'; use it only when the radiation in question is visible or optical light.
For physics 'radiation' use 放射; for releasing something use 放出; for beams aimed at something use 照射; 発散 covers diffusion or venting; 発光 is only light emission.
Usage comparisons are AI-assisted and cross-checked by multiple models; for study reference only
Japanese equivalents
See also
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