1.
arm
The upper limb of the body from shoulder to hand.
2.
skill, ability
One's ability or skill at something, especially a craft or profession.
腕 has two main meanings: the physical arm (from shoulder to hand) and skill or ability.
SENSE 1 — ARM:
Refers to the entire arm. Common compounds:
SENSE 2 — SKILL:
Commonly used to describe one's ability at a craft or profession:
- 腕がいい: to be skilled
- 腕を磨く: to polish one's skills
- 腕を上げる: to improve one's skills
- 腕を振るう: to show off one's skills
The skill sense is especially common for cooking, craftsmanship, and professional work.