inconsistent

American  

[in-kuhn-sis-tuhnt] / ˌɪn kənˈsɪs tənt /

adjective

1. lacking in harmony between the different parts or elements; self-contradictory.

   an inconsistent story.

   Synonyms:

   incoherent

2. lacking agreement, as one thing with another or two or more things in relation to each other; at variance.

   a summary that is inconsistent with the previously stated facts.

   Synonyms:

   irreconcilable, discrepant

3. not consistent in principles, conduct, etc..

   He's so inconsistent we never know if he'll be kind or cruel.

4. acting at variance with professed principles.

5. Logic. incompatible.

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inconsistent British  

/ ˌɪnkənˈsɪstənt /

adjective

1. lacking in consistency, agreement, or compatibility; at variance

2. containing contradictory elements

3. irregular or fickle in behaviour or mood

4. Also: incompatible.  maths (of two or more equations) not having one common set of values of the variables: x + 2 y = 5 and x + 2 y = 6 are inconsistent

5. logic (of a set of propositions) enabling an explicit contradiction to be validly derived

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Synonym Usage

Inconsistent, incompatible, incongruous refer to things that are out of keeping with each other. That which is inconsistent involves variance, discrepancy, or even contradiction, especially from the point of view of truth, reason, or logic: His actions are inconsistent with his statements. Incompatible implies incapability of close association or harmonious relationship, as from differences of nature, character, temperament, and the like: actions incompatible with honesty of purpose; qualities that make two people incompatible. Something that is incongruous is inappropriate or out of keeping, often to the point of being ridiculous or absurd: Incongruous characters or situations frequently provide a basis for comedy.

Other Word Forms

• inconsistently
  adverb

Etymology

Origin of inconsistent

First recorded in 1640–50; in- ³ + consistent

Explanation

Inconsistent describes something that's varied or irregular. So if you're supposed to floss every day, but you only remember every now and then, your commitment to oral hygiene could be called inconsistent. The adjective inconsistent first came into use in the 1640’s, with the sense of “not agreeing in substance or form.” Broken down into its roots, in plus consistent, the word literally means "not consistent." Behavior, results in lab experiments, and your cooking skills could all be described as inconsistent if they are irregular, spotty, and hard to predict.

Example Sentences

See Examples For:

inconsistent

However, after my father passed away, that support has been inconsistent — sometimes substantial and other times essentially nonexistent, without much explanation.

From MarketWatch ● Aug. 25, 2026

Since opening the evaluation, the agency has received more reports of losing brake assist, some of which have described issues inconsistent with GM’s description of a spindle failure.

From The Wall Street Journal ● Aug. 24, 2026

Every user I knew complained it was inconsistent, illogical, cluttered, had clunky navigation and ignored accessibility standards.

From Salon ● Aug. 24, 2026

By pooling results, researchers can draw stronger conclusions than they might from smaller individual studies, particularly when earlier findings have been inconsistent.

From Science Daily ● Aug. 23, 2026

Though some psi studies continue today, most major universities have ended their programs due to inconsistent findings, lack of usefulness, or outright fraud.

From "American Spirits" by Barb Rosenstock

Related Words

• conflicting
• contrary
• erratic
• illogical
• incompatible
• irreconcilable
• uncertain
• unpredictable