1A style, behavior, or idea that is currently popular and widespread; a fashion or trend.
今年はショートヘアが流行している。
Short hair is trendy this year.
あのアイドルグループの曲は若者の間で流行した。
That idol group's song became popular among young people.
流行に流されず、自分らしい服を選びたい。
I want to choose clothes that suit me, without being swept up in trends.
このダンスはSNSで一気に流行した。
This dance suddenly became a craze on social media.
2The widespread occurrence and spread of a disease over a period of time; an epidemic.
例年、1月から2月にかけてインフルエンザが流行する。
Every year, the flu spreads widely from January to February.
その地域では数年前に感染症が流行した。
An infectious disease was prevalent in that region a few years ago.
手洗いとうがいは病気の流行を防ぐのに効果的だ。
Washing hands and gargling are effective in preventing the spread of disease.