1) Comparatively still 2) Go between 3) Less agitated 4) Less freaked out 5) Less jumpy 6) Less nervous 7) Less ruffled 8) Less stormy 9) Less turbulent 10) Less upset 11) Mediator 12) More at ease 13) More collected 14) More like a mill pond 15) More peaceful 16) More placid 17) More relaxed 18) More sedate 1) Opiate 2) Valium 
• (n.) One who, or that which, makes calm.
Calm'er noun One who, or that which, makes calm.