1The progress or growth of something, becoming larger in scale or momentum; often used for technology, the economy, and similar areas.
この街は10年間で急速に発展した。
This town developed rapidly over the past ten years.
インターネットの発展によって仕事のやり方が大きく変わった。
The development of the internet has dramatically changed the way we work.
会社のさらなる発展を目指して新しい部署を作った。
We created a new department aiming for the company's further growth.
発展途上国への支援が話し合われた。
Support for developing countries was discussed.
2The way a situation or story progresses and unfolds into its next stage.
交渉は思わぬ発展を見せ、両者は合意に至った。
The negotiations took an unexpected turn, and the two sides reached an agreement.
小さな口論が思いがけない発展を遂げ、大きな騒動になった。
A small argument developed unexpectedly into a big commotion.
事件の発展を見守るしかなかった。
All we could do was watch how the incident would develop.
3A slang term, used mainly among gay men, referring to seeking out casual sexual encounters.
その公園は「発展場」として一部で知られていた。
That park was known in some circles as a 'hattenba' (cruising spot).