The compound adjective "three-fingered" is a transparent and descriptive formation native to English. Its first element, "three," descends from the Proto-Germanic numeral þrīz, which itself originates from the Proto-Indo-European root trei-, a fundamental numerical concept. The second element, "finger," derives from the Proto-Germanic fingraz, whose ultimate origin is uncertain but has been in use since the earliest stages of the language to denote the digits. The suffix "-ed," used to form adjectives from nouns, is a common feature in English, indicating "having the qualities of" or "provided with." Thus, the word's logic is entirely literal and compositional, directly describing the physical characteristic of possessing three fingers, a meaning that has remained stable since its formation.

Structure: three (number) + finger (body part) + ed (adjective suffix) - three: From Old English þrīe, þrēo, of Proto-Germanic origin; meaning the number 3. - finger: From Old English finger, of Proto-Germanic origin; meaning a digit of the hand. - ed: From Old English -ede, an adjective-forming suffix indicating possession or characteristics.