fill-up

The compound 'fill-up' is a modern English phrasal verb nominalization, combining two native Germanic elements. The verb 'fill' carries the core meaning of making something full, a concept traceable to the Proto-Indo-European root pelh₁- meaning "to fill." The particle 'up' functions as an intensifier, indicating the action is carried out to completion or to a brimming state. This logical pairing of an action with a completive particle is a common feature in English, creating a specific term often associated with refueling vehicles or satisfying hunger entirely. The term's literal sense of "filling completely" naturally extends to its colloquial use for a substantial meal.

Structure: fill (to make full) + up (completely) 'Fill' originates from Old English fyllan, meaning "to make full," derived from the Proto-Germanic root fullijaną. Its functional role is the core verb denoting the action. 'Up' originates from Old English upp, up, an adverb and preposition denoting upward direction or completion, from Proto-Germanic upp.