Real Dictionary

sap
countable noun: If you describe someone as a sap, you think they are foolish.
uncountable noun: Sap is the watery liquid in plants and trees.
verb: If something saps your strength or confidence, it gradually weakens or destroys it.

sap in American English 1
the juice that circulates through a plant, esp. a woody plant, bearing water, food, etc. to the tissues
to drain of sap
noun: the juice or vital circulating fluid of a plant, esp. of a woody plant
transitive verb: to drain the sap from

sap in American English 2
an extended, narrow trench for approaching or undermining an enemy position or fortification
to dig saps
to undermine by digging away foundations; dig beneath
intransitive verb: to dig a sap
noun: a deep, narrow trench constructed so as to form an approach to a besieged place or an enemy's position
transitive verb: to approach (a besieged place or an enemy position) by means of deep, narrow trenches protected by gabions or parapets

sap in American English 3
a blackjack, short club, etc.
to hit on the head, or knock out, with a sap

sap in British English 1
abbreviation for: South African Police
noun: a solution of mineral salts, sugars, etc, that circulates in a plant

sap in British English 2
noun: a deep and narrow trench used to approach or undermine an enemy position, esp in siege warfare
noun acronym for: Standard Assessment Procedure: the recognized performance indicator for measuring energy efficiency in buildings
verb: to undermine (a fortification, etc) by digging saps