rxj

The only 3 letters with no definition, so here's one:
1)A person who stands out in any environment.
2) An ex who only texts you so your new gf thinks you're cheating on her.
3) Where everything is triangles.
4) A word with too many different definitions.

1) "He sucks at hide and seek, it's rxj."
2) "My ex is being rxj!"
3) "This place is rxj, it should be called 'Triangle palace!'"
4) "Rxj is rxj."