hav ‧ oc /ˈhævək/ BrE AmE noun [uncountable]
[ Date: 1400-1500 ; Language: Anglo-French ; Origin: Old French havot 'destruction, disorder' ]
a situation in which there is a lot of damage or a lack of order, especially so that it is difficult for something to continue in the normal way SYN chaos
cause/create havoc
A strike will cause havoc for commuters.
policies that would wreak havoc on the country’s economy
Rain has continued to play havoc with sporting events.