Colloquialism
Colloquial Language
noun, の adjective
Vulgar language isn't necessarily bad words, or something like that. It's just rougher and not as standard as standard language. It is a colloquialism or colloquial language.
This is a jukugo word that uses the on'yomi readings of the kanji. You should be able to read this on your own.
この俗語はアメリカ独特の表現です。
This colloquialism is an expression unique to America.