It's been popping up lately. It's meant as a smear on dynamically typed languages, because dynamic has a positive connotation and untyped is decidedly negative. Pretty similar in intention to uni-typed.
http://stackoverflow.com/questions/23282683/is-clojure-uni-t...
Edit: Sorry, learned something new just now. I'm very, very wrong.
Untyped is where operations are valid on everything because it's all a sequence of bits.
Dynamic is completely different and refers to when the type is discovered.
Sorry. However, Javascript is definitely dynamically typed.