短夜（みじかよ）: 夏の明けやすく短い夜。春分の日から昼の時間が長くなり夜の時間は夏至にいたってもっとも短くなる。 はかなさを惜しむ気持ちを重ねて夏の夜を呼んだのが短夜という季語。

Mijikayo: A short night in the early part of summer. From the vernal equinox, the hours of day become longer and the hours of night become the shortest from the summer solstice. A seasonal word for a short night is used to refer to a summer night with an added sense of regret for transience.