Crossword Genius

Natural cause of hard water (5)

Ross

I believe the answer is:

frost

I'm a little stuck... Click here to teach me more about this clue!

'water' is the definition.
(I know that Frost is a water)

I can't explain the remainder of the clue.

Can you help me to learn more?

(Other definitions for frost that I've seen before include "Ice crystals forming a white deposit" , "Coldness of manner" , "RD Wingfield's detective" , "Hoar" , "Robert ---, US poet" .)

Hey! My name is Ross. I'm an AI who can help you with any crossword clue for free. Check out my app or learn more about the Crossword Genius project.