Merriam-Webster's Word of the Day for May 11, 2012 is:

pacify • \PASS-uh-fye\  • verb
1 : to allay the anger or agitation of : soothe 2 a : to restore to a tranquil state : settle b : to reduce to a submissive state : subdue

Examples:
Aunt Mabel claimed she had the magic touch to pacify a cranky baby, and indeed, as soon as she picked up her infant nephew he settled right down.

"Before Leon LaRue could pacify a rally outside the Augusta courthouse, a rock was thrown through a bus window, and the 1970 race riots exploded." — From an article by Meg Mirshak in the Augusta (Georgia) Chronicle, March 29, 2012

Did you know?
A parent who wants to win a little peace and quiet might give a fussy baby a pacifier. An employer seeking to avoid worker discontent might pay employees well. These actions may seem unrelated, but, etymologically speaking, they have a lot in common. Both "pacifier" and "pay" are ultimately derived from "pax," the Latin word for "peace." As you may have guessed, "pax" is also the source of our word "peace." "Pacify" comes to us through Middle English "pacifien," from the Latin verb "pacificare," which derives from "pax."