The phrase "grows feeble" refers to the gradual decline in physical or mental strength or ability. Synonyms for this phrase include "weakens", "deteriorates", "declines", "diminishes", and "fades." Other synonyms may include "degenerates", "decays", "wanes", "falters", and "slumps." These terms all convey a sense of gradual decline or loss of vigor and vitality. The phrase "grows feeble" can apply to a range of contexts, from the aging process to the decline of health or well-being. Understanding the various synonyms for this phrase can help to convey the specific nuances of this gradual decline.