Other forms: fluids
A fluid is a substance that flows, whether liquid or gas. Bodily fluids, brake fluid, drink plenty of fluids.
The word covers both liquids and gases, which is the point of having it — anything that cannot resist a shearing force is a fluid. As an adjective it means flowing and easily changed, as in a fluid situation. The Latin fluere means to flow.
1nounfluidA substance that flows, liquid or gas.
“Drink plenty of fluids when you have a fever.”
2adjectiveeasilyFlowing and easily changed.
“Our plans for the summer are still fluid, so nothing is booked yet.”
fluid is a substance.
Latin fluidus comes from fluere, to flow. Fluent, influence and flux come from the same flowing.
Proto-Indo-European
*bʰel- (blow)
Latin
fluidus
Middle English
fluid
English, today
fluid
From Middle English fluid, from Latin fluidus. From Middle English fluid, from Latin fluidus (“flowing; fluid”), from Latin fluō (“to flow”), from Proto-Indo-European bʰleh₁- (“to swell; surge; overflow; run”). Akin to Ancient Greek φλύειν (“to swell; overflow”). Not related to English flow, which is a native, inherited word from plew-, but is distantly related from English bleat.
Etymology from Wiktionary, CC BY-SA