What is this? Lathe, mill, other?

[kd4gij]

I used to have a router bit set that had a bit like that plus a 45deg one like it.

laminate trimmer bit​

 

[Illinoyance]

Laminate trimmer definitely.

 

[ARC-170]

I put a file on it and it's nice and hard, so I guess it's a laminate trimmer of some sort.