1) Calmly 2) Composedly 3) Coolly 4) Evenly 5) In a calm manner 6) In a calm way 7) In a peacefully serene manner 8) In a tranquil manner 9) In an imperturbable way 10) In peace 11) In tranquil manner 12) Peacefully 13) Quietly 14) Steadily 15) Tranquilly 16) Unperturbedly 17) Unworriedly 1) Demurely 2) Quietly 
• (adv.) In a serene manner; clearly. • (adv.) With unruffled temper; coolly; calmly.
Se·rene'ly adverb 1. In a serene manner; clearly. « Now setting Phœbus shone serenely bright.» Pope. 2. With unruffled temper; coolly; calmly. Prior. 
[adv] - in a peacefully serene manner
adverb in a peacefully serene manner; `I had the feeling that he was waiting, too--serenely patient`