Meaning:
If something looks mouth-watering, that means it looks tasty.

The Origin Of “Mouth-Watering”
This phrase likely comes from the fact that when humans see or smell food, their mouths might produce more saliva than usual. The “water” mentioned in the phrase is not actually water, but saliva that the mouth produces. So when a person sees or smells some delicious food, they might begin to “water” at the mouth. Interestingly, saliva is made up mostly of water.
This phrase “mouth watering” has been used since at least the mid-18th century. Its meaning back then looks the same as today. For example, in the European Magazine and London Review, March 1784, the saying is written in a story and one of the characters from the story says:
“I see him this moment before me–his huge paunch blown up like a feather bed, his gouty legs resting on two down pillows, his eyes sparkling, his mouth watering, the napkin tucked under his rosy gills, and the whole pie devour’d in imagination before he had tasted a morsel of it.”
Example Sentences
- I can’t wait to get home from a long day at work so I can eat. I know my wife has prepared a mouth-watering dinner for us.
Related Example:
- That pizza looks finger-lickin’ good, I’ll take a slice.