v. Slang 1. To make someone relax; cause someone to become more genial and pleasant: A nice cool drink would mellow me out right now. A nap might mellow out the kids.
2. To relax; become genial and pleasant: Hey, don't get so upset; just mellow out! We stayed at home and mellowed out all day.
3. To make something less intense or less striking: I added some white to the paint to mellow the color out a little bit. We added candles to mellow out the atmosphere.