There are plenty of synonyms for the word "weakens," which means to make something or someone less strong or effective. Some of the most common synonyms include "diminishes," "lessens," "reduces," "deteriorates," "undermines," "erodes," and "compromises." Other options include "debilitates," "enfeebles," "sap," "weary," "fatigues," and "exhausts." Each of these synonyms can be used in various contexts, depending on the specific meaning and implication you want to convey. For example, "diminishes" might suggest a gradual decline, while "undermines" implies a deliberate effort to weaken something. Regardless, these synonyms are useful for adding variety and precision to your writing or speech.