infalliblein‧fal‧li‧ble /ɪnˈfæləbəl/ adjective 
Examples
No expert is infallible. an infallible memory2something that is infallible always works or has the intended effect → fail-safe: He had an infallible cure for a hangover.—infallibly adverb—infallibility /ɪnˌfæləˈbɪləti/ noun [uncountable]
ExamplesEXAMPLES FROM OTHER DICTIONARIES
Thesaurus- Banks claim their cash-dispensing computers are infallible.
- Computer spell checkers are useful but far from infallible.
- DNA testing is an almost infallible method of identification.
- Having been divorced three times, Aden admits he's far from infallible.
- Juries are not infallible. Innocent people are convicted, and guilty people go free.
- There is no infallible way of predicting exactly what the weather will be like.
Longman Language Activatoralways effective► reliable
1always right and never making mistakes OPP fallible: · The system is new, but so far it seems to be reliable.a reliable way/method etc of doing something · Eating sensibly and taking regular exercise is a fairly reliable method of losing weight.· In Africa, cellular phones are often the only reliable way of communicating.
► surefire certain to be effective or successful: · Thursday night's line-up includes such surefire attractions as 'The Simpsons' and 'Friends'.a surefire way to do something/of doing something: · I know a surefire way to get a car started on a freezing winter morning.a surefire solution to something: · There's no surefire solution to the problem of improving the company's performance.a surefire recipe for success/disaster (=something that is certain to be successful or not successful): · Going on holiday with my parents would be a surefire recipe for disaster.
► foolproof a method, system, or plan that is foolproof is always effective, because it is simple to understand and operate, and cannot go wrong: · I thought this method was foolproof until four customer orders went missing.· Each article goes through a foolproof system of checking which ensures that there are no mistakes in the final text.a foolproof way to do something/of doing something: · There's no foolproof way to judge whether someone is the right person for the job.
► infallible a method or system that is infallible always produces the right result and never goes wrong: · Banks claim their cash-dispensing computers are infallible.an infallible way to do something/of doing something: · There is no infallible way of predicting exactly what the weather will be like.
► never fails/can't fail/works every time spoken use this to tell someone that a method is always effective, especially when you have used it successfully before: · It's a very simple technique, but it never fails.· If I'm having trouble sleeping, having a hot bath at night works every time.· You should try this recipe. It's so easy that you can't fail.
to be correct in what you say or think► be right · You're right - there's not going to be enough food for everyone.be right about · Durrell is absolutely right about the importance of software to the local economy.be right about one thing (=say this when part of someone's opinion or what they say is right, but the rest is wrong) · It's not a great album, but Samuels was right about one thing: it's going to sell in the millions.be right in saying/thinking etc · Moore is right in saying that the present tax system is unfair.
► get something right to say the correct facts or details when you are telling a story, describing an event etc: · Make sure you get people's names right when you're sending out the invitations.· "I learned," he stopped, wanting to get the words right, "I learned I was selfish."
► be correct in saying/thinking etc if someone is correct in saying or thinking a particular fact, the fact is correct, especially when they are not sure if it is correct or not: · Monroe was correct in saying that unemployment has dropped in the last five years.· I believe I am correct in saying that two of the original computer languages were Cobol and Prolog.· The jury was correct in thinking that the prosecution had not presented a strong case.
► be on the right track to not yet know the complete answer to a question or problem, but be close to finding it because you are already partly correct: · No, that's not quite right, but you're on the right track.· Researchers are still a long way from finding a cure for the disease, but many seem confident they are on the right track.
► hit the nail on the head/put your finger on it to say something that is exactly right and that is the answer to a problem which people have been thinking about for a long time: · Garson hits the nail on the head - at the heart of the abortion debate is a religious issue.· Wyman put his finger on it when he said the truth was complicated.
► be spot on British informal to be exactly right, especially by guessing correctly: · "Is the answer 42?" "You're spot on! Well done, Mary."
► infallible someone or something that is infallible is always right and never makes mistakes - use this especially to say that this is not usually true or is extremely rare: · Computer spell checkers are useful but far from infallible.· Juries are not infallible. Innocent people are convicted, and guilty people go free.
No expert is infallible. an infallible memory2something that is infallible always works or has the intended effect → fail-safe: He had an infallible cure for a hangover.—infallibly adverb—infallibility /ɪnˌfæləˈbɪləti/ noun [uncountable]