Spreading or dissemination (of information, rumors, viruses, etc.); commonly used online to mean sharing or spreading content.
フェイクニュースが瞬く間に拡散した。
Fake news spread in no time.
感染拡大を防ぐため、情報の拡散を抑える必要がある。
To prevent the spread of infection, it's necessary to curb the dissemination of information (i.e., misinformation).
SNSで『拡散希望』と書かれた投稿が多く見られる。
You can often see posts on social media saying 'Please share' (literally 'wish to spread').
Diffusion (physical spreading) of light, gas, particles, etc.; a scientific/technical meaning referring to spreading in space.
この素材は光の拡散性が高く、柔らかい光を作るのに適している。
This material has high light-diffusing properties and is suitable for creating soft lighting.
有害物質の拡散を防ぐために隔離措置が取られた。
Isolation measures were taken to prevent the diffusion of hazardous substances.