the compound adjective 'thick-necked' is a transparent formation from native english elements. the old english adjective þicce and noun hnecca evolved directly into modern english 'thick' and 'neck', retaining their core physical meanings. the addition of the adjectival suffix '-ed', also of old english origin, follows a common pattern for creating descriptive terms denoting possession of a physical feature, such as 'long-haired' or 'blue-eyed'. the literal meaning describing a physical build later extended metaphorically to characterize stubbornness, implying a rigid, unyielding posture akin to a strong neck that does not turn easily.

Structure: thick (adjective) + neck (noun) + ed (adjective suffix) - thick: from old english þicce (dense, viscous, solid). functions as the descriptive adjective. - neck: from old english hnecca (the part of the body connecting the head to the shoulders). functions as the noun being modified. - ed: from old english -od, a suffix forming adjectives from nouns, indicating 'having the quality of'.