1. informal To become more pleasant or agreeable in nature. He always nicens up when we hang out on our own, so I don't understand why he's so mean to me around others. It's pretty stormy at the moment, but it's supposed to nicen up this afternoon.
2. informal To make someone or something more pleasant or agreeable in nature. The company likes to nicen up its image by touting all the little perks it offers its employees. I've been trying to nicen my dog up for a while now, but nothing seems to be working. In the sequel, the author nicens up the antagonist from the first book by examining his tragic backstory.
See also: up
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