1. Literally, to make something taste sweeter. A noun or pronoun can be used between "sweeten" and "up." I like to use honey to sweeten up my tea. Just use a dash of sugar to cut through the acidity of the tomatoes in the sauce, but not so much that you end up sweetening it up.
2. To make something more pleasant, appealing, or enticing, especially from a financial perspective. A noun or pronoun can be used between "sweeten" and "up." I really don't want to look after Tommy this weekend, but buying me that video game I've been asking for would really sweeten up the deal. Desperate to close the sale, the owners tried to sweeten it up by offering to knock $10,000 off the price of the house.
3. To cause someone to be more pleasant, amiable, or magnanimous. A noun or pronoun can be used between "sweeten" and "up." I thought moving to Florida would sweeten up my cranky old uncle, but he's still as cantankerous as ever. He tried to sweeten her up with an expensive gift, but she still wouldn't give him the time of day.
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.
sweeten someone up
to make someone more pleasant. I had hoped that a week in the Caribbean would sweeten him up. The trip sweetened him up, but not for long.
sweeten something up
to make something taste sweeter. Where is the sugar? I need to sweeten this up a little. A little sugar will sweeten up the coffee.
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs. © 2002 by The McGraw-Hill Companies, Inc.
1. To make something sweet or sweeter: The recipe instructs to sweeten up the sauce with a tablespoon of sugar. I usually add some honey to my tea to sweeten it up.
2. To make some offer more appealing: The phone company sweetened up their deal by throwing in a free phone. If you're still unimpressed with our proposal, we can sweeten it up with a great benefits package.
The American Heritage® Dictionary of Phrasal Verbs. Copyright © 2005 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.