The compound adjective "steep-walled" is a transparent modern English formation. Its first element, "steep," originates from the Old English stēap, which conveyed concepts of height and precipitousness. The second element, "walled," derives from Old English weall, referring to a defensive structure, combined with the adjectival suffix -ed. The term logically combines these two descriptive roots to create a vivid geographical or architectural term, specifically denoting a natural feature or structure characterized by sides that are both steep and wall-like in their verticality and imposing appearance.

Structure: steep (sharp slope) + walled (having walls) - steep: From Old English stēap (high, lofty, deep, prominent). An adjective describing a sharp rise or fall. - walled: From Old English weall (rampart, dike, stone wall) + the suffix -ed, forming an adjective meaning "having walls" or "enclosed by walls".