Adjective no-fail (not comparable) That cannot fail; sure to succeed. 1996, Joan Benjamin, Barbara W. Ellis, Rodale's No-Fail Flower Garden:What Is a No-Fail Flower Garden? That's an easy question. A no-fail flower garden is one that looks great and grows well for you. 2018, Angela Block, Redesign, page 157:A wonderful friend gave me this no fail caramel recipe. Use it to top other desserts but it pairs well in these yummy little trifle cups.