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to expand; to swell (out); to get big; to become inflated
オーブンの中でパン生地がふっくらと脹らんだ。
The bread dough puffed up nicely in the oven.
新しいプロジェクトへの夢が脹らんでワクワクする。
Dreams for the new project are swelling and I'm excited.
風船が脹らむにつれて割れそうで少し怖い。
As the balloon inflates, it looks like it might pop, which is a bit scary.