noun
ADJECTIVE
▪ big , chief , main , major , primary ( esp. AmE ), prime , real , true , worst
▪
In the battle to stay slim, the biggest ~ is lack of exercise.
▪ likely , obvious , possible
VERB + CULPRIT
▪ hunt , hunt for (both esp. BrE )
▪
Police hunting the ~s have condemned the attack.
▪ apprehend ( esp. BrE ), catch , discover , find , identify , track down