erratic

American  

[ih-rat-ik] / ɪˈræt ɪk /

adjective

1. deviating from the usual or proper course in conduct or opinion; eccentric.

   erratic behavior.

   Synonyms:

   capricious, unstable, unpredictable

   Antonyms:

   stable, regular, consistent

2. inconsistent, irregular, or unpredictable.

   Many factors affect purchasing power, such as inflation and erratic swings in the stock market.

3. having no certain or definite course or pattern; wandering; not fixed.

   erratic winds.

4. Geology. noting or pertaining to a boulder or the like carried by glacial ice and deposited some distance from its place of origin.

5. (of a lichen) having no attachment to the surface on which it grows.

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noun

1. an erratic or eccentric person.

2. Geology. an erratic boulder or the like.

erratic British  

/ ɪˈrætɪk /

adjective

1. irregular in performance, behaviour, or attitude; inconsistent and unpredictable

2. having no fixed or regular course; wandering

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noun

1. a piece of rock that differs in composition, shape, etc, from the rock surrounding it, having been transported from its place of origin, esp by glacial action

2. an erratic person or thing

Other Word Forms

• erratically adverb
• erraticism noun
• nonerratic adjective
• unerratic adjective

Etymology

Origin of erratic

First recorded in 1325–75; Middle English, from Latin errāticus, equivalent to errāt(us) (past participle of errāre “to make a mistake, err” ( err ) + -icus -ic

Explanation

The adjective erratic describes things that are unpredictable, unusual, and that deviate from the norm. An erratic quarterback might completely confuse his receivers waiting for a pass. Like its linguistic relative, error, the adjective erratic means "deviating from the norm," or "wrong." It also implies behavior or qualities that are unpredictable or odd. The word comes from the Latin verb errare, or "to wander" off course. In the field of geology, a rock that is erratic is unlike others in its environment because it has been transported by glacial activity. Likewise, someone driving a car that veers out of its lane is said to be driving erratically.

Example Sentences

Meanwhile, the 2025 novel “Unfit” by Ariana Harwicz, about a mother losing her children in a custody battle, uses erratic crayon scribbles on its cover.

From Los Angeles Times • Mar. 16, 2026

World number one Scottie Scheffler, who had an erratic level-par 72 in round one, is among the later starters, alongside England's Tommy Fleetwood.

From BBC • Mar. 13, 2026

The erratic Chinese air activity has created uncertainty about Beijing’s intentions amid global events.

From The Wall Street Journal • Mar. 12, 2026

Pankaj Nathe joined Sahyadri Farms in the cooperative's early days, and now heads agricultural research and certification, developing grape varieties more resilient to erratic weather.

From Barron's • Feb. 18, 2026

But the erratic Arctic temperatures plunged again to more than – 50°F. Three of the crew members returned barely coherent; the other four were unable to move, stranded miles away from the ship.

From "American Spirits" by Barb Rosenstock

Related Words

• abnormal
• arbitrary
• bizarre
• capricious
• eccentric
• inconsistent
• irregular
• mercurial
• uncertain
• unreliable
• unstable
• unusual
• volatile
• wayward
• weird
• whimsical