Antonyms for the word strengtheners include weakener, enervator, debilitator, and enfeeblement. These are terms used to describe things that reduce, deplete, or impair strength or vigor. A weakener, for example, might refer to a medicine that lowers a person's energy levels or makes them feel tired. An enervator might describe a substance that saps the vitality from a person, making them feel sluggish, dull, or lethargic. Debilitators similarly refer to things that weaken or impair a person's physical or mental faculties, while enfeeblements refer to conditions that undermine the body's strength and resilience. In contrast, 'strengtheners' are substances or practices that enhance, reinforce or stimulate strength or vigor in a person, helping them to perform better and or stay healthy.