sap

The word 'sap' has a deep Germanic lineage, tracing back to the Old English sæp, which referred to the vital fluid or juice of a plant. This term is cognate with similar words in other Germanic languages, such as Middle Dutch sap and Old High German saf, all sharing the core concept of a flowing liquid or juice. The semantic journey from this concrete botanical meaning to the abstract verb sense of "to weaken" is metaphorical, drawing a parallel between draining a plant of its life-sustaining fluid and gradually depleting a person's strength or a structure's foundation. The secondary noun sense meaning a foolish person emerged in the 18th century, likely from the idea of being "empty of sense" or "drained of intelligence."

This word is a simplex form. It originates from Old English sæp, meaning "vital fluid of a plant, juice." Its functional role is as a base noun and verb.