also: つゆざむ
noun
cold at the end of autumn when dew turns to frost
Archaic seasonal word (kigo) used in classical poetry and haiku to evoke the chill of late autumn. Not used in modern everyday speech.
露寒の頃、野山は霜に覆われる。
In the season of dew-cold, fields and mountains are covered with frost.
この句の「露寒」は晩秋の冷え込みを表す季語だ。
The word 'tsuyusamu' in this haiku is a seasonal term expressing the chill of late autumn.
寒露 is one of the 24 solar terms (around October 8), while 露寒 is a more poetic, archaic term for the cold felt when dew freezes.
Compound of 露 (tsuyu, 'dew') and 寒 (samu, 'cold'). The reading つゆざむ shows rendaku voicing of the second element.