modified
calm, tranquil, clear, pellucid, limpid, unruffled, translucent, undisturbed, undimmed, peaceful, halcyon, idyllic, smooth, quiet, still, composed, imperturbable, cool, cool-headed, sedate, level-headed, content, satisfied, patient, reconciled, easygoing, placid, comfortable, cheerful; see also calm 1, 2, tranquil 1, 2.
Antonyms agitated, disturbed, ruffled. See syn. study at calm.calm.