noun
unwanted hair; superfluous hair
Commonly used in beauty and grooming contexts for body hair one wishes to remove.
夏に向けてムダ毛の処理を始めた。
I started dealing with unwanted hair for the summer.
ムダ毛が気になる季節になった。
It's the season when unwanted hair bothers me.
Rarely used kanji form; 徒 is an ateji for むだ.
Compound of 無駄 (むだ, 'useless, wasteful') and 毛 (け, 'hair'), with rendaku voicing け → げ.