Unreliable vs. Uncertain — What's the Difference?
Edited by Tayyaba Rehman — By Fiza Rafique — Published on January 17, 2024
Unreliable refers to a lack of dependability, while uncertain indicates a lack of sureness or confidence.
Difference Between Unreliable and Uncertain
Table of Contents
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Key Differences
An unreliable person or thing is not able to be trusted or depended upon for accuracy or honesty. Uncertainty, on the other hand, relates to unpredictability or doubt about the future or about the truth of something. Unreliable sources may provide information that often proves to be false or inaccurate, while uncertain situations are characterized by a lack of definite knowledge or a definitive outcome.
When describing an unreliable individual, one implies that the person has a history or a pattern of not fulfilling promises or commitments. In contrast, calling a situation uncertain does not necessarily imply any fault or pattern of behavior; it simply states that the outcome or truth is not clear. Unreliable often carries a negative connotation, implying a fault in something or someone, whereas uncertain can be value-neutral and merely descriptive of a state of limited knowledge.
The unreliability of a machine means it does not perform consistently or as expected. For someone uncertain about a decision, the issue lies not in any inherent defect, but in indecision or a lack of sufficient information to make a clear decision. Unreliable is typically used to describe consistent failures or inconsistencies, while uncertain refers to a single instance or ongoing state of doubt or indecision.
In data analysis, unreliable data is that which cannot be trusted to represent the truth due to errors or manipulation, whereas uncertain data is that which is subject to a range of possible values or interpretations due to variability or incomplete information. Therefore, while unreliability is often a systemic issue, uncertainty can be a momentary condition awaiting further clarification or information.
When one expects a car to start every morning, and it does not, the car is considered unreliable. However, if the weather forecast for tomorrow is a 50% chance of rain, the weather is uncertain—it may or may not rain, and the forecast reflects this lack of certainty. Unreliable suggests a problem to be fixed or avoided, while uncertain speaks to the need for more information or acceptance of ambiguity.
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Comparison Chart
Definition
Not consistently good in quality or performance; not able to be trusted.
Not able to be relied on as known or constant; not known or definite.
Connotation
Generally negative, implying fault or shortcoming.
Neutral, related to unpredictability or lack of information.
Context Usage
Often used to describe people or things with a track record of inconsistency.
Used when an outcome is unknown or when there is doubt.
Dependability
Indicates a known pattern of failing to be dependable.
Does not imply a pattern, simply an unknown state.
Associated Emotion
Frustration or distrust due to past experiences.
Hesitation or contemplation due to possible outcomes.
Compare with Definitions
Unreliable
Not deserving of trust.
His unreliable testimony led to the acquittal.
Uncertain
Not able to be assured or confident.
She was uncertain about the path ahead.
Unreliable
Likely to change unpredictably.
The stock market has been particularly unreliable this year.
Uncertain
Subject to change or variability.
The weather this weekend is uncertain.
Unreliable
Prone to failure or inconsistency.
The old truck is too unreliable for long trips.
Uncertain
Characterized by indecision.
His plans for college are still uncertain.
Unreliable
Not able to be trusted for accuracy.
I skipped the meeting because the notification system is unreliable.
Uncertain
Not known or established; questionable
Domestic changes of great if uncertain consequences.
Unreliable
Undependable in keeping promises.
He's unreliable; he never shows up when he says he will.
Uncertain
Not determined; undecided
Uncertain plans.
Unreliable
Marked by or exhibiting a lack of reliability.
Uncertain
Not having sure knowledge
An uncertain recollection of the sequence of events.
Unreliable
Not reliable.
Uncertain
Subject to change; variable
Uncertain weather.
Unreliable
Not reliable; untrustworthy. See Reliable.
Alcibiades . . . was too unsteady, and (according to Mr. Coleridge's coinage) "unreliable;" or perhaps, in more correct English, too "unrelyuponable."
Uncertain
Unsteady; fitful
Uncertain light.
Unreliable
Liable to be erroneous or misleading;
An undependable generalization
Uncertain
Not certain; unsure.
Unreliable
Not to be trusted
Uncertain
Not known for certain; questionable.
Tomorrow's weather is uncertain.
Unreliable
Not worthy of reliance or trust;
In the early 1950s computers were large and expensive and unreliable
An undependable assistant
Uncertain
Not yet determined; undecided.
Unreliable
Dangerously unstable and unpredictable;
Treacherous winding roads
An unreliable trestle
Uncertain
Variable and subject to change.
Unreliable
Lacking a sense of responsibility
Uncertain
Fitful or unsteady.
Uncertain
Unpredictable or capricious.
Uncertain
(with "the") Something uncertain.
Uncertain
Not certain; not having certain knowledge; not assured in mind; distrustful.
Man, without the protection of a superior Being, . . . is uncertain of everything that he hopes for.
Uncertain
Irresolute; inconsonant; variable; untrustworthy; as, an uncertain person; an uncertain breeze.
O woman! in our hours of ease,Uncertain, coy, and hard to please!
Uncertain
Questionable; equivocal; indefinite; problematical.
From certain dangers to uncertain praise.
Uncertain
Not sure; liable to fall or err; fallible.
Soon bent his bow, uncertain in his aim.
Whistling slings dismissed the uncertain stone.
Uncertain
To make uncertain.
Uncertain
Lacking or indicating lack of confidence or assurance;
Uncertain of his convictions
Unsure of himself and his future
Moving with uncertain (or unsure) steps
An uncertain smile
Touched the ornaments with uncertain fingers
Uncertain
Not established beyond doubt; still undecided or unknown;
An uncertain future
A manuscript of uncertain origin
Plans are still uncertain
Changes of great if uncertain consquences
Without further evidence his story must remain uncertain
Uncertain
Not established or confirmed;
His doom is as yet unsealed
Uncertain
Not firm or secure;
Balancing three boxes in an uncertain pile
Uncertain
Not certain to occur; not inevitable;
Everything is uncertain about the army
The issue is uncertain
Uncertain
Subject to change;
A changeable climate
The weather is uncertain
Unsettled weather with rain and hail and sunshine coming one right after the other
Uncertain
Not safe from danger or mishap;
Faced an uncertain future
An unsure existence
Uncertain
Not consistent or dependable;
An uncertain recollection of events
A gun with a rather uncertain trigger
Uncertain
Ambiguous (especially in the negative);
She spoke in no uncertain terms
Uncertain
Not clearly established or defined.
The rules of the game seemed uncertain to the new players.
Uncertain
Having unpredictable outcomes.
The future of the company is uncertain after the merger.
Common Curiosities
Does unreliable mean the same as dishonest?
Not necessarily; unreliable can refer to inconsistency or failure in performance, not just dishonesty.
Is technology unreliable or uncertain?
Technology can be unreliable if it often malfunctions; it's uncertain if its future developments or effects are unknown.
Can a person be uncertain but reliable?
Yes, someone can be unsure about certain matters yet still be consistently dependable.
Are emotions unreliable or uncertain?
Emotions can be both unreliable in their inconsistency and uncertain in how they will evolve.
Is uncertainty always a bad thing?
No, uncertainty can lead to opportunities and encourage open-mindedness.
Can an uncertain future be exciting?
Yes, the unpredictability can be stimulating and offer a sense of adventure.
Can a fact be uncertain?
No, a fact by definition is something with evidence; however, its interpretation can be uncertain.
How do you deal with unreliable people?
Set clear expectations, verify their actions, and limit reliance on them.
Can an unreliable tool still be useful?
It can be, but with the understanding that it may not work properly at all times.
What is an unreliable witness?
An unreliable witness is someone whose account of events is not consistently trustworthy or credible.
Can unreliable information be corrected?
Yes, if the source of unreliability is identified and fixed.
Are scientific theories unreliable or uncertain?
They can contain elements of uncertainty, but generally are not labeled unreliable if they are the current best explanation.
How can one become more reliable?
By developing consistent habits, improving skills, and fulfilling commitments.
Is it possible to make uncertain situations more predictable?
Yes, through gathering more information and experience.
How does uncertainty affect decision-making?
It can lead to hesitation, require risk assessment, and necessitate contingency planning.
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Written by
Fiza RafiqueFiza Rafique is a skilled content writer at AskDifference.com, where she meticulously refines and enhances written pieces. Drawing from her vast editorial expertise, Fiza ensures clarity, accuracy, and precision in every article. Passionate about language, she continually seeks to elevate the quality of content for readers worldwide.
Edited by
Tayyaba RehmanTayyaba Rehman is a distinguished writer, currently serving as a primary contributor to askdifference.com. As a researcher in semantics and etymology, Tayyaba's passion for the complexity of languages and their distinctions has found a perfect home on the platform. Tayyaba delves into the intricacies of language, distinguishing between commonly confused words and phrases, thereby providing clarity for readers worldwide.
