The word 'sunken' is the adjectival form derived from the past participle of the verb 'sink'. Its core component, 'sink', originates from the Proto-Germanic verb sinkwaną, meaning "to sink, subside," which itself has a probable Proto-Indo-European root related to falling or descending. The addition of the '-en' suffix, a common Germanic participial adjective ending (seen in words like 'broken' or 'woven'), transforms the verbal action into a descriptive state. Thus, 'sunken' logically describes something that has undergone the process of sinking, resulting in its current condition of being submerged, lower, or hollowed out.

Structure: sunk (past participle of sink) + en (adjective-forming suffix) - sunk: From Old English sincan (to become submerged, descend). Germanic origin, related to Dutch zinken and German sinken. In this word, it is the past participle form of the verb 'sink'. - en: A suffix of Germanic origin used to form adjectives from nouns or verbs, often meaning "made of" or "having the qualities of". In this case, it creates a participial adjective from the past participle.