11 Words For A Person Who Doesn’t Do What They Say They Will

It is certainly frustrating when a person says they will do something but, for whatever reason, doesn’t do it! Whether this is intentional or not, it is fairly common, and so let’s look at some of the ways to describe such people.

Words For A Person Who Doesn't Do What They Say They Will

The preferred words to describe a person who does not do what they say they will, are “irresponsible”,“unreliable” or “deceptive”. How the words are chosen can tell us about the attitude, ability and motivation of the person. Let’s look at some examples to explain how these are used.


“Irresponsible” is a great way to describe someone who doesn’t care much about the consequences of following through on their promise to do something. They may lose interest, give up, never get around to it, or simply forget about it.

The irresponsible person doesn’t care much what others think. They may sincerely intend to do what they say they will do, or just agree to do something in the moment, then lose interest. Their own happiness is more important than their word.

According to The Cambridge Dictionary, the definition of “irresponsible” is “not thinking enough or worrying about the possible results of what you do”.

  • If you want the job done properly, you should give it to Anne because the younger students are still careless and irresponsible.
  • Don’t trust him to deliver the letter; he is so irresponsible.
  • The waiter promised he would be here on time, but he is half an hour late; that’s just so irresponsible!


If a person is “unreliable”, you cannot depend on them to follow a task through to completion.  This may be because they are not too concerned about their reputation or, even when they sincerely want to deliver on their promise, lack the competence or underestimate the time required.

Someone “unreliable” will let you down, whether intentionally or not. They cannot to be trusted to do what they say they will do. 

The definition of “unreliable,” according to The Cambridge Dictionary, is “not able to be trusted or believed.”

  • He is a friend of the defendant, so he cannot be trusted to tell the truth; he would be an unreliable witness.
  • I would ask her to help me with this, but she let me down the last time; she is too unreliable.
  • We have stopped depending on the local bus service; the timetable is so unreliable.


When there is little doubt that the person deliberately chose to say one thing while holding the intention to do something entirely different, that person may be labelled “deceptive”. They have been caught in their attempt to mislead.

When a person has been found to be deceptive once, it is difficult to trust them again.

The definition of “deceptive” According to The Cambridge Dictionary, the objective of the “deceptive” person is in “making you believe something that isn’t true”.

  • Her behaviour is deliberately deceptive; she wants you to believe that she has only your best interests at heart.
  • He presented a deceptive account of the meeting, so that the shareholders believed everything was going to plan.
  • Her reputation was destroyed when her deceptive interpretation of the conversation was exposed.


The procrastinator may want to do what he said he would do, but, when it comes to actually delivering the work, the spirit is willing but the flesh is weak. The procrastinator will always put off until tomorrow what he could do today. Often tomorrow never comes!

The Cambridge Dictionary  defines the “procrastinator” as “someone who keeps delaying things that must be done.”

  • She always has great ideas but rarely follows through with her actions; it is a pity that she is such a procrastinator.
  • He has a reputation for being a habitual procrastinator, so we always allow an extra week for the essay to be handed in.
  • She would be the most successful composer in history, if she weren’t such a procrastinator.


A “fickle” person tends to change their mind with their mood – which is quite often! If their intentions are prone to frequent change, they can go back on their promise on a whim. Someone “fickle” is, by nature, unpredictable and cannot be trusted to do what they say they will.

The “fickle” person, according to The Cambridge Dictionary, is “someone who is likely to change their opinion or feelings without warning.”

  • He is quite fickle when it comes to his loyalties; he seems to favour one company over another depending on his mood.
  • Don’t depend on them to support your campaign; they are quite fickle when it comes to politics.
  • He told the chef he was a vegetarian, but his preferences are quite fickle and he changes his mind from week to week.


Similar to “fickle”, “unpredictable” also refers to someone who says one thing, but is likely to change their opinion or mood, and do something else. The person may not mean any harm, but it is their inconsistency that means they are often guilty of not doing what they say they will.

The Cambridge Dictionary, definition of “unpredictable” is “likely to change suddenly and without reason, and, therefore, not able to be predicted (=expected before it happens) or depended upon.”

  • He is likely to change his mind without warning and so his results are often unpredictable.
  • Don’t depend on their help on Saturday as their attendance is infrequent and unpredictable.
  • He can deliver results which are either outstanding or extremely disappointing, and so his work is unpredictable.


A “wily” person intends to deceive. They say they will do one thing while planning to do something entirely different. They display the characteristics of the fox, which is also described as “crafty” or “cunning”. They use their intelligence to fool and, therefore, get what they want.

The Cambridge Dictionary defines “wily” as “often willing to use tricks to achieve an aim”.

  • Even though her tales of great bravery and service seemed authentic, they were later revealed to be a wily ploy to win their trust.
  • Her kind promise to look after their house was only a wily plan to steal the diamonds.
  • They make wily promises to support us while, at the same time, destroying our reputation.  


Another good word to describe the action of someone who deliberately misleads by saying they will do one thing, while plotting to do the opposite is to “double-cross”. The person is then a “double-crosser”. This word is often used among criminals, proving there is often no honour among thieves!

The definition of to “double-cross”, according to The Cambridge Dictionary, is “to deceive someone by working only for your own advantage in the (usually illegal) activities you have planned together”.

  • When he opened the safe, the money had disappeared and he realized he had been double-crossed by the gang.
  • Her intention to double-cross her friend was exposed when her plan to escape was discovered.
  • We were double-crossed by the spy who gave our names to the police.


“Disingenuous” is a great word to use when you are fairly sure that someone hasn’t been completely honest with you, but you want to stop short of accusing them of lying. The disingenuous person is, therefore, slightly unreliable and, usually, wily.

The definition of “disingenuous” according to The Cambridge Dictionary, is “slightly dishonest, or not speaking the complete truth.”

  • His reply was later found to be disingenuous as he had deliberately misled the inquiry.
  • His disingenuous remark was interpreted to mean he did not know the driver, but he had met him on several occasions.  
  • Her response, while not completely untrue, was a disingenuous attempt to fool her audience.


“Perfidious” is a strong word to choose when a person stands accused of a serious act of treachery. While stopping short of using the fiery accusation of lying, a “perfidious” person can be shown to have said one thing but maliciously acted in the opposite direction.

The definition of “perfidious,” according to The Cambridge Dictionary, is “unable to be trusted, showing no loyalty”.

  • The committee were shocked by his perfidious actions to undermine the authority of the chairman.
  • After all her acts of kindness and loyalty, she was repaid by his perfidious gossip.
  • The article was a perfidious attempt to deceive the people.


To call a person a “liar” is a strong accusation and you must be sure of the evidence to support this. However, it can be a good name for a person who doesn’t do what they say they will do, especially if they often behave like this.

The definition of “liar”, according to The Cambridge Dictionary, is “someone who tells lies”.

  • They were shocked by his publication of stories that were simply not true, and had no other choice but to assume he was a liar.
  • She did not want to call him a liar, but, in the end, the evidence could not be denied.
  • He says that he is an honest tradesman, but how can you trust the words of a compulsive liar?

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