腕毛 is read as うでげ (udege) and means arm hair.
うでげ
udege
うでどけい
wristwatch
うでまえ
ability
うで
arm
わんりょく
physical strength
わんぱく
naughty
うでぐみ
folding one's arms
わんしょう
armband
わんそくどうぶつ
brachiopod
うでのみせどころ
opportunity to show one's abilities
うでたて
push-up
うでだて
showing off one's physical strength
うでがあがる
to gain in skill