Weaken v. t. : To make weak; to lessen the strength of; to deprive of strength; to debilitate; to enfeeble; to enervate; as, to weaken the body or the mind; to weaken the hands of a magistrate; to weaken the force of an objection or an argument.

Weaken v. t. : To reduce in quality, strength, or spirit; as, to weaken tea; to weaken any solution or decoction.

Weaken v. i. : To become weak or weaker; to lose strength, spirit, or determination; to become less positive or resolute; as, the patient weakened; the witness weakened on cross-examination.

Example:
What is the word for activities designed to Weaken the established government?

Taxonomy
Merriam-Webster Online Dictionary, Dictionary, webster, intensity, Word Games, loss, health, Webster Online Dictionary with audio pronunciations, thesaurus, effective power, glossary, english, language, ESL, Search, Inflected, ened, transitive verb.

Defination from the web:
weaken from the Merriam-Webster Online Dictionary with audio pronunciations, thesaurus, Word of the Day, and word games. ... synonyms weaken, enfeeble, debilitate, undermine, sap, cripple, disable mean to lose or cause to lose strength or vigor. ...