frail

When describing people, "frail" often suggests a loss of strength due to age or long-term illness. It is more sympathetic than simply saying someone is "weak." When describing objects, it means the item is poorly made or thin. In these cases, "fragile" is a common synonym, though "fragile" often refers to things that break easily even if they are high quality (like glass). Avoid using this word for temporary weakness, such as feeling tired after a workout; use it only for permanent or long-term delicacy.