What's the difference between the word "liquid" and "fluid"?

[JamesWatson]

Hi,

What's the difference between the English word "liquid" and "fluid"?
For example, "US liquid gallon" vs "US fluid ounce". Can we say "fluid gallon" and "liquid ounce", too?

Thanks in advance.

[JamesWatson]

Have a good weekend to you all.

[Joe]

Hi,

What's the difference between the English word "liquid" and "fluid"?
For example, "US liquid gallon" vs "US fluid ounce". Can we say "fluid gallon" and "liquid ounce", too?

Thanks in advance.

Fluids have no fixed shape and easily fit any shape imposed on them externally, for example a liquid or gas. Sometimes fluid and liquid can be used interchangeably but not always. Molten magma flowing from a volcano has no fixed shape. It's fluid, but I wouldn't call it liquid.

[JamesWatson]

Thanks Joe for your explanation.