What does sap mean?
Sap has a small range of memorable meanings. As a noun, it most literally refers to the fluid that flows through plants and trees, carrying water, minerals, and sugars; “tree sap” is its commonest established expression. In dated informal English, however, a sap is a foolish or gullible person, a sense that can sound affectionate or mockingly familiar in older writing and dialogue. As a verb, sap means to weaken or drain something of its vital force, as in a prolonged illness that sapped her strength. The verb is especially associated with formal and literary English, while the liquid sense is ordinary and widespread. Together, the meanings create a useful semantic link: sap is what sustains a plant, and a person or thing that has had its strength removed has been “sapped.”
A foolish or gullible person, especially in dated informal use; also, the watery fluid that circulates through a plant or tree.
"The sap in the maple tree began to flow as the temperature rose."
The sense meaning a foolish person is old-fashioned and insulting. The plant-fluid sense is standard and usually uncountable, though “saps” can refer to people in the older sense.
To drain or weaken something, especially by gradually removing its strength, vitality, or essential resources.
"The long siege sapped the defenders' resolve."
Common in formal and literary contexts; its past tense is “sapped” and its present participle is “sapping.”
The plural is chiefly used in the dated sense of foolish people and is uncommon for the plant fluid.
"The novel portrayed its political rivals as a group of gullible saps."
Tree sap is often called the plant's blood, but it is a poetic description rather than a scientific one: it transports water, minerals, and sugars through the plant.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does sap come from?
The plant-fluid sense comes from Old English sæp, meaning the juice or fluid of a plant. This word belonged to the Germanic family and has relatives in forms such as German Saft, Swedish saft, Danish saft, and Old Norse saf. The noun meaning a simpleton developed later as a figurative expression, while the verb meaning to drain or weaken developed from the idea of extracting sap or vital strength.
Related word forms
How sap is actually used
The noun meaning a foolish person is old-fashioned and generally insulting, though it can appear in humorous or deliberately nostalgic contexts. The plant-fluid sense is standard in British and American English. The verb is more formal and literary than everyday alternatives such as weaken, drain, or undermine.
Easily confused with sap
Sap is the fluid within a plant, whereas a sop is bread or food soaked in liquid.