From Longman Dictionary of Contemporary Englishan outside chancean outside chancePOSSIBLEa very small possibility that something will happen Ireland still have an outside chance of winning. → outside
Examples from the Corpus
an outside chance• Here are two more from the downs with an outside chance and one from Wendover in Buckinghamshire.• There is also an outside chance Cadbury may itself be a bid target.• Norman pitched his into the heart of the green and had an outside chance for birdie.• Some shrewd Iowa pols also see an outside chance for former Gov. 