The compound adjective "well-fed" is a transparent construction from native English elements. The adverb "well," with Proto-Germanic origins meaning "according to one's wish," intensifies the state described by the participle "fed," derived from the Old English verb for nourishing. This literal combination, "having been fed well," directly conveys the concept of good nourishment. Over time, it solidified into a standard adjective describing a person or animal that receives ample, often high-quality, food, frequently implying a visible, healthy, or even plump physical condition as a result.

Structure: well (in a good manner) + fed (having been given food) - well: From Old English wel, meaning "in a good manner, satisfactorily." It functions as an adverb modifying the participle. - fed: The past participle of the verb feed, from Old English fēdan, meaning "to give food to." It functions as the core verbal element describing the state of having received food.