also: ラッシュ・アワー
noun
Refers to the peak traffic periods in the morning and evening when roads and trains are most crowded.
朝のラッシュアワーは電車がとても混みます。
Trains are very crowded during the morning rush hour.
ラッシュアワーを避けて出勤する。
I commute avoiding rush hour.
Specifically refers to the commuting rush, while ラッシュアワー is a broader term for peak traffic hours.
Borrowed from English 'rush hour'.