(uncountable) The juice of plants of any kind, especially the ascending and descending juices or circulating fluid essential to nutrition.

(uncountable) The sapwood, or alburnum, of a tree.

Any juice.

(figurative) Vitality.

(slang, countable) A naive person; a simpleton.

(countable, US, slang) A short wooden club; a leather-covered hand weapon; a blackjack.

(military) A narrow ditch or trench made from the foremost parallel toward the glacis or covert way of a besieged place by digging under cover of gabions, etc.

(transitive) To drain, suck or absorb from (tree, etc.).

(transitive, figurative) To exhaust the vitality of.

(transitive, slang) To strike with a sap (with a blackjack).

(transitive) To subvert by digging or wearing away; to mine; to undermine; to destroy the foundation of.

(transitive, military) To pierce with saps.

(transitive) To make unstable or infirm; to unsettle; to weaken.

(transitive) To gradually weaken.

(intransitive) To proceed by mining, or by secretly undermining; to execute saps.