Meaning & use
fluid
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Meanings
nouncountable or uncountable
A substance, either liquid or gas, that can flow and take the shape of whatever holds it.
Grammar: Uncountable in general (drink more fluid) and countable for kinds: cleaning fluids.
Patterns
- drink fluids
- a fluid for something
The doctor told him to drink plenty of fluids.
Brake fluid had leaked onto the garage floor.
Cleaning fluids should be kept away from children.
adjectivecomparabletechnical
Able to flow easily like a liquid.
Grammar: Usually describes a substance that moves freely: a fluid mixture.
The paint was fluid enough to spread without a brush mark.
Warm honey becomes more fluid.
adjectivecomparableapproving
Smooth, graceful, and continuous in movement or style, with no awkward breaks.
Grammar: Often describes motion, writing, or performance: a fluid stroke; fluid prose.
Patterns
- fluid in something
The dancer's movements were fluid and effortless.
Her fluid writing style makes the book easy to read.
He gave a fluid performance on the piano.
adjectivecomparable
Not fixed or settled and likely to change, as plans, situations, or identities may.
Grammar: Used about things that are still changing: the situation is fluid.
The plan is fluid and may change next week.
Politics in the region remains fluid.
Word forms
| plural | fluids |
|---|---|
| comparative | more fluid |
| superlative | most fluid |
Common combinations
- drink fluids
- Rest and drink plenty of fluids when you have a cold.
- body fluids
- Wash your hands after contact with body fluids.
- fluid motion
- The swimmer's fluid motion cut through the water.
- fluid situation
- The situation is fluid, so check for updates.
- hydraulic fluid
- The jack uses hydraulic fluid to lift the car.
Synonyms and how they differ
- liquid
- Liquid names only substances in the liquid state, while fluid also includes gases.
- flowing
- Flowing describes movement happening now, while fluid describes a lasting quality.
- flexible
- Flexible means easy to adapt, while fluid suggests constant natural change.
- graceful
- Graceful stresses elegance of movement, where fluid stresses smoothness and lack of breaks.
Opposites
Word family
Commonly confused: fluid or liquid? fluid or fluent?
fluid vs liquid
All liquids are fluids, but not all fluids are liquids; air is a fluid but not a liquid.
fluid vs fluent
Fluent describes smooth speech in a language, while fluid describes smooth movement or change.
Practice
The rules for the trip are still ___, so we may change the route.
Choose one answer.
Fluid means not yet settled and open to change. Solid, rigid, and final all mean the opposite.
Make it your own
Write a sentence using “fluid”, then check it and compare it with the examples above.