Fluid

How to spell fluid

5 letters · 2 syllables

How to pronounce fluid

Say the part in capitals loudest.

What does fluid mean?

1. nounA substance, such as a liquid or gas, that flows and has no fixed shape.
2. adjectiveSmooth and flowing, or able to change easily and not fixed.

Fluid in a sentence

• noun

  The mechanic checked the brake fluid before the long drive.

• adjective

  The dancer moved with a graceful, fluid motion across the stage.

• noun

  After surgery the nurse encouraged her to drink plenty of fluid.

• adjective

  Our travel plans remain fluid until the flights are confirmed.

Where does fluid come from?

Language of origin: Latin

This word descends from the Latin verb fluere, meaning 'to flow', the same root that gives us 'flow' relatives like 'fluent', 'influence', and 'flux'. The Latin adjective fluidus described something capable of flowing, a quality of liquids and gases. English took it in through French and directly from Latin in the late 1500s, first as an adjective for substances that flow freely, and soon also as a noun naming such a substance. Over time the word stretched into figurative use, describing situations, plans, or movements that are smooth, changeable, or not fixed. The tricky part of the spelling is the 'ui' vowel pair: the 'u' sits before the 'i', echoing the Latin fluidus, so it helps to picture the related word 'fluent' and keep the same flu- opening.

How the word is built

• flu- (from Latin fluere: to flow)
• -id (adjective/noun suffix)