Phthisical is an archaic adjective associated with phthisis, a wasting disease historically used especially for pulmonary tuberculosis. In literary traditions shaped by the eighteenth and nineteenth centuries, it may evoke the pale, weakened figure whose body diminishes through fever, coughing, and loss of breath. Poets use the term in elegiac or Gothic settings to explore mortality, confinement, poverty, and the uneasy idealization of sickly beauty. Its old-fashioned medical register can also place a poem in an earlier era, where illness was both intimate experience and social fate.

"Phthisical" means afflicted with phthisis (tuberculosis or pulmonary consumption), a disease marked by severe coughing, fever, and progressive wasting away. In 19th-century Romantic literature, phthisis was famously romanticized as the "artist's disease"—associated with tragic youth, intense passion, pale beauty, and heightened creative genius (exemplified by John Keats). Students analyzing 19th-century verse should examine how phthisical imagery reflects the era's fascinating, tragic link between bodily decay and aesthetic sensitivity. Related terms include tubercular, consumptive, emaciated, and wasting.