The word "phlegm" takes on a range of meanings in literature, often straddling the worlds of medicine and metaphor. In medical and physiological contexts, authors invoke it as one of the ancient humors—associated with coldness and moisture—to explain bodily functions and ailments, as seen in discussions of purging and expectoration ([1], [2], [3]). Meanwhile, it also emerges as a vivid descriptor of physical states, from the literal coughing up of mucus ([4], [5], [6]) to its role in remedies for coughs and respiratory issues ([7], [8], [9]). Beyond its literal sense, "phlegm" is employed metaphorically to convey an emotional or temperamental quality: a reserved, even indifferent disposition is often characterized as having "British phlegm" or a similar quality that tempers one's response to circumstance ([10], [11], [12], [13]). In this dual capacity, the term enriches literary narratives by linking physiological theories with character traits and moods.