ghost friend

a ghost friend is an acquaintance that act like friends with, but they don't state that they're your friend out loud. maybe someone you know is nice to you and always greets you (maybe they're just friendly/nice, but you can still consider them as a ghost friend)

although others may think you have a literal friend that's a ghost, you can explain the other definition for it.

i bumped into my ghost friend today, it was so funny yet embarrassing, lol

in math, my ghost friend and i laughed so hard, i love them