fluctuate
/ˈflʌk.tʃu.eɪt/To rise and fall repeatedly and irregularly over time. Things that fluctuate do not stay at one level — they keep changing in unpredictable ways.
- Oil prices fluctuate depending on global supply and demand.
- Her energy levels fluctuate throughout the day.
- The river's water level fluctuates significantly between the dry and wet seasons.
Adinary Nuance
"Fluctuate" is often confused with "vary," "oscillate," and "waver," but each word fits a different situation. "Vary" is the most general — it simply means things are not the same at different times, with no suggestion of pattern or direction. "Oscillate" implies a regular, rhythmic swing between two fixed points, and sounds more technical or scientific. "Waver" usually describes a person's resolve or opinion becoming unsteady, not external quantities. "Fluctuate" is the right choice when you want to stress irregular, repeated up-and-down movement over time — prices, temperatures, exchange rates, or even moods — especially in academic or formal writing.
In other languages
- Vietnamese
- dao động
- Spanish
- fluctuar
- Chinese
- 波动
- Japanese
- 変動する
- Korean
- 변동하다
Etymology
From Latin "fluctuare," meaning "to undulate" or "to move in waves," derived from "fluctus" (a wave) and the root "fluere" (to flow). The word entered English in the 17th century and has been used in economic and scientific writing ever since.
Common phrases
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Related words
Frequently asked questions
- Is 'fluctuate' formal or informal?
- Fluctuate is a formal word. It is common in academic writing, business reports, news articles, and IELTS essays. In casual speech, people usually say 'go up and down' instead.
- What is the difference between 'fluctuate' and 'vary'?
- 'Vary' just means things are different at different times, with no specific pattern. 'Fluctuate' adds the idea of repeated, irregular movement up and down — it is more precise and more academic.
- Can I use 'fluctuate' in IELTS Writing Task 1?
- Yes — it is an excellent choice for Task 1 graphs and charts that show data rising and falling over time, such as prices, temperatures, or employment figures.
- Can 'fluctuate' describe a person's mood or feelings?
- Yes. You can say a person's mood, confidence, or motivation fluctuates. This usage is common in psychology and medical writing, and it sounds natural in formal essays too.