v.1. To dilute or weaken something by adding water: The dishonest bartender watered down the liquor. The cook watered the sauce down.
2. To decrease the value of a share of stock, or the value of some group of shares, by increasing the number of shares available for sale: Investors are concerned that stock option grants will water down their holdings. I hope that decision doesn't water the stock values down.
3. To reduce the strength or effectiveness of something: In the end, the legislation was watered down by multiple amendments. The speaker watered his message down with lots of boring stories.
4. To wet the surface of something entirely: The fire department watered down the houses near the brush fire. The road crew watered the dusty road down.