/ sæp; NAmE / noun , verb
■ noun
1.
[ U ] the liquid in a plant or tree that carries food to all its parts :
Maple syrup is made from sap extracted from the sugar maple tree.
2.
[ C ] ( informal , especially NAmE ) a stupid person that you can easily trick, or treat unfairly
■ verb
( -pp- ) [ vn ] sap sth | sap sb (of sth) to make sth/sb weaker; to destroy sth gradually :
The hot sun sapped our energy.
Years of failure have sapped him of his confidence.
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WORD ORIGIN
noun sense 1 and verb Old English sæp , probably of Germanic origin. The verb (dating from the mid 18th cent.) is often interpreted as a figurative use of the notion “drain the sap from”, but is derived originally from the verb sap , in the sense undermine .
noun sense 2 early 19th cent.: abbreviation of dialect sapskull person with a head like sapwood , from sap (in the sense sapwood ) + skull .