In temperament theory, phlegmatic is one of the four temeraments, along with sanguine, choleric, and melancholic. Phlegmatics are self-confident, kind, calm, and rational.
Origin 1300–50; "cool, calm, self-possessed," and in a more pejorative sense, "cold, dull, apathetic," 1570s, from lit. sense "abounding in phlegm (as a bodily humor)" (mid-14c.), from O.Fr. fleumatique, from L.L. phlegmaticus, from Gk. phlegmatikos "abounding in phlegm"
Example The generally phlegmatic (2) doctor was disconcerted at the blood she saw in her phlegmatic (3) patient's tissue. While attempting to remain calm and in control for the sake of her patient, she also made sure not to appear uncaring or phlegmatic (1) in the face of an emergency.