H2O
The universal solvent
It's called salt solution; frequently used is the word brine.
A person who is frequently ill can be called "sickly" or "prone to illness."
"Water Closet" is a frequently used synonym for "toilet".
Doldrums
A continent .
This is frequently call an "antonym".
Lists of Frequently Asked Questions are often called FAQs (after the first letters in each word in the phrase).
Salted water is frequently used for vegetables pickling.
For drinking water fine sand is frequently used.
Salted water is frequently used for vegetables pickling.
a cuboidActually, it can be called (and is more frequently called) a rectangular prism :)
This is frequently call an "antonym".