single-arm

The compound adjective "single-arm" is a modern English formation that transparently combines two native elements. "Single" traces back to Latin singulus, meaning "one, individual," which entered English via Old French. "Arm" is a foundational Germanic word from Old English earm, referring to the limb from shoulder to hand. The compound's logic is entirely literal, directly describing an action, apparatus, or condition involving or intended for just one arm, such as in specific exercise equipment or medical conditions. Its formation follows the common English pattern of adjective-noun compounding to create a precise descriptive term.

Structure: single (one) + arm (limb) - single: From Latin singulus (one, individual). Functional role: Adjective-forming base meaning "one, sole". - arm: From Old English earm (arm, forelimb). Functional role: Noun base denoting the upper limb of the human body.