1 [singular] informal : something that is very easy to do
▪ This recipe is a cinch. ▪ This dish is a cinch to make.2 [singular] chiefly US, informal — used to say that something will certainly happen or that someone will easily do something ▪ It's a cinch that he'll win the election. = He's a cinch to win the election.3 [count] US : a strap that holds a saddle on a horse
▪ This recipe is a cinch. ▪ This dish is a cinch to make.