Emily Dickinson Lexicon

SAP, v.t. [Fr. saper; It. zappare; Arm. sappa; It. zappa, a spade; zappone, a mattock. The primary sense is probably to dig or to thrust.]

1. To undermine; to subvert by digging or wearing away; to mine. Their dwellings were sapp'd by floods. – Dryden.
2. To undermine; to subvert by removing the foundation of. Discontent saps the foundation of happiness. Intrigue and corruption sap the constitution of a free government.