noun, noun which may take the genitive case particle 'no'
Refers to a single arm, often in contexts of physical ability or disability.
彼は片腕で重い荷物を持ち上げた。
He lifted the heavy luggage with one arm.
noun
right-hand man; trusted assistant
Figurative use for a person who is indispensable support, like a right arm.
彼は社長の片腕として会社を支えている。
He supports the company as the president's right-hand man.