From Diablo Wiki
Shouts are Barbarian skills that can act as buffs for the Barbarian, debuffs for enemies, or direct attacks, depending on the skill and the runestone effect present. Shouts are non-targeted skills; they all emit directly from the Barbarian, and generally add a skill effect of some sort that lasts for a limited duration.
The term "warcry" was generally used for this sort of skill in Diablo II, but since there is an actual skill called "War Cry" in Diablo III, using "shout" is clearer. (Confusingly, there were Warcry skills called " " and " " in Diablo II.)