There are several synonyms for the phrase "in poor health" that can be used to describe someone's physical or mental condition. Some examples include: sickly, unwell, ailing, weak, feeble, frail, debilitated, infirm, fragile, and delicate. These words can describe a variety of health issues, ranging from minor ailments to more serious illnesses or chronic conditions. Depending on the degree of severity and context, some synonyms may be more appropriate than others. It is important to choose the right synonym to accurately convey the state of someone's health and avoid misunderstandings.