Of a person or a personal attribute, quality, etc.: not affected by passion or emotion, dispassionate; controlled, deliberate, not hasty; calm…

Of bearing, movement, etc.: Showing no trace of haste, impatience, or the like.

Of the face, bearing, etc.: Made calm or tranquil; properly adjusted, undisturbed by emotion; expressive of gravity or self-possession.

Of a person, his mind, circumstances, etc.: Calm, tranquil, untroubled, unperturbed. Of the countenance: Expressive of inward calm, unruffled.

Cheerful, genial; soft, calm. Now rare.

Of a person, behaviour, etc.: composed, self-assured. Cf. self-poised, adj.

Originally U.S. Of a person: that has achieved a state of inner peace or harmony; at ease with oneself, serene; emotionally well balanced. Cf. centre…