Which word would not describe a state of strength or health?

The term that would not describe a state of strength or health is "feckless." This word typically refers to someone who is ineffective, weak, or lacking in initiative or strength. In a broader context, it implies a sense of ineffectiveness or lack of vigor, which stands in stark contrast to the idea of strength and health.

In contrast, "robust" conveys a sense of being strong, healthy, and vigorous. It is often used to describe both physical and mental attributes that indicate resilience and robustness. "Exigent" can mean pressing or demanding, and while it may not directly imply strength, it can suggest a situation that requires vigor and promptness. "Scathing" typically refers to critical remarks that can be harsh or severe. Although it does not intrinsically represent strength or health, it still does not align with the notion of weakness or ineffectiveness as "feckless" does.