one-arm

The compound adjective 'one-arm' is a straightforward combination of two native English words. 'One' derives from the Old English numeral 'ān', a foundational concept of singularity. 'Arm' originates from the Old English 'earm', a term for the upper limb, shared across Germanic languages. When combined, these morphemes create a literal descriptor meaning "having a single arm," which logically extends to describe actions, devices, or conditions involving or limited to the use of one arm. Its formation follows the typical English pattern of combining number and body part to specify a physical attribute or capability.

Structure: one (single) + arm (limb) one: From Old English 'ān', meaning "one, a single". It is a numeral root of Proto-Germanic origin, functioning as a quantifier. arm: From Old English 'earm', meaning "arm, forelimb". It is a noun of Proto-Germanic origin, referring to the upper limb of the human body.