one-up in British English adjective. informal. having or having scored an advantage or lead over someone or something.

One-up is defined as to try to have an advantage over someone. An example of one-up is when you always feel the need to correct everyone around you to make yourself look smarter than them. verb.

1UP means An Extra Life in an online gaming context. The term 1UP came to prominence with the Super Mario games. It is now commonly used by gamers to denote they have been rewarded with “An Extra Life.”

sex up. 1. slang To make someone or something more sexually attractive or alluring. vulgar slang To engage in sexual intercourse or activity with someone.

put (one) up to (something) To cause, persuade, or pressure one to do or engage in something considered mischievous, ill considered, or malicious. He was always putting his younger brother up to playing pranks on other people.

The truth is that one-uppers are often just insecure individuals who are desperate to make an impression. In knowing how to best deal with them, you must first understand their motives.

So when it says 1-up girl it means that there’s no other girl like the one its talking about.

UP1

What is another word for one-up?