Top definition
Portmanteau from "platonic" and "unicorn". A platonicorn is a person involved in a platonic relationship with a couple, such as the three involved persons get along with each other, together or separately.
You're welcome to come over for drinks on Tuesday night, but we'll be hanging out with our platonicorn, so you might feel like a 4th wheel or something.
by skaya September 27, 2020