expression, noun-modifying (irregular)
calm and composed; unruffled; imperturbable
A literary set phrase describing a person's demeanor as unhurried, dignified, and unflappable, even under pressure. Often used in formal or written contexts.
He always has a calm and composed manner that puts those around him at ease.
The gentleman with an unruffled demeanor slowly rose from his seat.
泰然自若 is a more formal, four-character idiom meaning complete self-possession, similar in register to 悠揚迫らぬ but with a stronger nuance of unshakable calm.
A set phrase combining 悠揚 (yūyō, 'calm and unhurried') with the classical negative form 迫らぬ (semaranu, 'not pressing/urgent'). The exact origin is uncertain, but it likely arose in literary Japanese to describe an unhurried, dignified composure.