fluids
n. C / U B1 Intermediate US //ˈfɫuədz// UK //flˈuːɪdz// flu·ids
n. any liquid or gas that can flow easily. You often hear doctors use this word when they tell you to drink more water or juice.
n. substances, such as liquids or gases, that have no fixed shape and yield easily to external pressure. Often used in medical or scientific contexts to refer to the total liquid intake or output of a body.
The doctor told me to drink plenty of fluids while I have a cold.
Mechanics checked the car's brake and transmission fluids to ensure the vehicle was safe for the long trip.
Usage
Usually plural when referring to medical hydration or automotive liquids; uncountable when referring to the general state of matter.