Derived from terms such as “cognitive spectrum”, “cognitive diversity”, and “cognitive divergence”. Essentially an updated take on the late 90s and early 2000s use of the word by retarded or tard.
A female, often young, whose interests involve staying in at night in comfy clothes and watching chick flicks (often in oversized comfy clothing usually belonging to the cosy girl's boyfriend).
Paul: Hey there's Chloe, I wonder if she's any fun.
Owen: Nah, I hear she's a cosy girl
To possess amazing qualities and be a generally cool person. Cossy is a term to describe something that cannot be described with words like: Cool, Rad, Sweet, Gnarly Etc.
If one is awesome enough to be called Cossy, you know damn right that they are cooler than cool!