also: ひゃくにちかつら
noun
long-haired wig used in kabuki; thick growth (metaphorical)
Primarily a kabuki term for a specific long-haired wig. Metaphorically used to describe a very thick growth of hair or plants, but this usage is rare and literary.
歌舞伎の舞台で、百日鬘をつけた役者が登場した。
An actor wearing a hyakunichikazura wig appeared on the kabuki stage.
その森はまるで百日鬘のような深い緑に覆われていた。
The forest was covered in deep green, as if it were a hyakunichikazura.
General term for wig; 百日鬘 is a specific type used in kabuki.
Compound of 百日 (hyakunichi, 'one hundred days') and 鬘 (kazura/katsura, 'wig'). The name likely refers to the wig's length or the time it takes to grow such long hair.