1
: having no fixed course : wandering
an erratic comet
2
3
: transported from an original resting place especially by a glacier
an erratic boulder
4
archaic
: nomadic
: one that is erratic (see erratic entry 1)
especially
: a boulder or block of rock transported from its original resting place especially by a glacier
Did you know?
Erratic can refer to literal "wandering". A missile that loses its guidance system may follow an erratic path, and a river with lots of twists and bends is said to have an erratic course. Erratic can also mean "inconsistent" or "irregular". So a stock market that often changes direction is said to be acting erratically; an erratic heartbeat can be cause for concern; and if your car idles erratically it may mean that something's wrong with the spark-plug wiring.
Synonyms
Examples of erratic in a Sentence
Adjective
My sinker has been my most erratic pitch. And when your foundation pitch is lacking, you have to go to other pitches. My sinker has been in and out, but mostly out.
—
Orel Hershiser, in New York Times, 9 May 1999
In winning his two-month match in Yugoslavia against Boris Spassky, 10 games to five, Bobby Fischer was erratic, which was hardly surprising considering his two-decade layoff, but there were times when he played more brilliantly than anybody could have expected.
—Sports Illustrated, 16 Nov. 1992
Over the centuries, in erratic ways, men have constructed a world in which they are relatively free of many kinds of threatening or harmful stimuli …
—B. F. Skinner, Beyond Freedom and Dignity, (1971) 1972
so far your effort to land a summer job has been very erratic
because of your erratic attendance at practice, you're in danger of being cut from the team
Orel Hershiser, in New York Times, 9 May 1999
In winning his two-month match in Yugoslavia against Boris Spassky, 10 games to five, Bobby Fischer was erratic, which was hardly surprising considering his two-decade layoff, but there were times when he played more brilliantly than anybody could have expected.
—Sports Illustrated, 16 Nov. 1992
Over the centuries, in erratic ways, men have constructed a world in which they are relatively free of many kinds of threatening or harmful stimuli …
—B. F. Skinner, Beyond Freedom and Dignity, (1971) 1972
so far your effort to land a summer job has been very erratic
because of your erratic attendance at practice, you're in danger of being cut from the team
Recent Examples on the Web
Justin Birnbaum, Forbes, 25 Oct. 2024
The bottom line: As Election Day nears, Trump has not tapered his off-script controversial comments — rather, his language has grown more erratic and hyperbolic.
—Avery Lotz, Axios, 20 Oct. 2024
Keely Larson, Ars Technica, 4 Jan. 2023
Speidel was inspired to create these artworks from her fascination with glacial erratics, a type of rock that once was carried inside glacial ice and traveled hundreds of miles sometimes across thousands of years to its current resting spot.
—Nickole Kerner Bobley, Houston Chronicle, 25 Apr. 2020
See all Example Sentences for erratic 
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Opinions expressed in the examples do not represent those of Merriam-Webster or its editors.
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Adjective
Notorious for his fiery personality and erratic behavior, Steinbrenner replaced his managers 20 times in his first 23 seasons—firing and then rehiring Billy Martin five times—and changed publicity directors 13 times in 26 years, according to Sports Illustrated.
—Justin Birnbaum, Forbes, 25 Oct. 2024
The bottom line: As Election Day nears, Trump has not tapered his off-script controversial comments — rather, his language has grown more erratic and hyperbolic.
—Avery Lotz, Axios, 20 Oct. 2024
Noun
Car-sized erratics embedded in ice were carried both within the lake area and as much as 500 miles from the lake by flood waters—some of the erratics weighed up to eight and a half tons.
—Keely Larson, Ars Technica, 4 Jan. 2023
Speidel was inspired to create these artworks from her fascination with glacial erratics, a type of rock that once was carried inside glacial ice and traveled hundreds of miles sometimes across thousands of years to its current resting spot.
—Nickole Kerner Bobley, Houston Chronicle, 25 Apr. 2020
See all Example Sentences for erratic
Dictionary Entries Near erratic
Cite this Entry
“Erratic.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/erratic. Accessed 28 Nov. 2024.
Copy CitationMedical Definition
erratic
adjective
er·rat·ic
ir-ˈat-ik 
1
: characterized by lack of consistency, regularity, or uniformity
an erratic pulse
2
: deviating from what is ordinary or standard
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