Pacem is the Latin word for peace, as used in the phrase "dona nobis pacem" (which means "grant us peace"), and the phrase "si vis pacem, para bellum" (which means "if you want peace, prepare for war"). The "c" in pacem can be pronounced classically with the hard C sound, like the "k" sound, as in the word "kind," or the more modern way (since around the middle ages) like the "ch" sound, as in the word "church."