sap

The fluid circulating in a plant, carrying nutrients.

"The tree's sap was flowing freely in the spring."

To gradually weaken or exhaust someone's strength or energy.

"The illness sapped her strength and vitality."

To undermine or weaken the foundations of something.

"His constant criticism sapped my confidence."

A foolish or easily deceived person; a dupe.

"He was a complete sap, easily fooled by her lies."