To make someone, something, or oneself appear more visually attractive or appealing. A noun or pronoun can be used between "pretty" and "up." My sisters wanted to pretty me up for my date, but I told them I was happy with how I looked. The real estate agent wants us to pretty the house up a bit before we put it on the market. She said she wanted to pretty herself up before going out, but she's been in there for nearly an hour.