adj. causing great harm, or death, or something else real bad.
DAMN that was a pernicious fart.
by Emetic August 28, 2003
Describes something that really messes you up. Most of the time you can't tell at the beginning but before you know it, it really fucks you up.
Person 1: It ain't worth it bro, you know Prozac is pernicious. Don't take it.

Person 2: Too late, I can't get off of it now.

Person 1: Damn, I hope you don't get erectile dysfunction like that other kid.

Person 2: Too late for that too...
by Moses D. October 8, 2011
Having a harmful effect especially in a stubble or gradual way
The pernicious weed has spread all over the flower bed
by Banditzzi May 26, 2022
adj: an all purpose word for something cool, hip, or awesome; or evil, twisted, and sick. Also functions well as a nickname.
Example of cool: Dude, Lord of the Rings: ROTK was SO pernicious!

Example of evil: Our algebra homework last night was PERNICIOUS! I didn't get any sleep!
by Niph April 24, 2004
Freyalise set up us the bomb; Yawgmoth will pay for his treachery; Freyalise performed her pernicious deed.
by The Ravenclaw Seeker April 27, 2004
Having love for somebody that causes harm towards you, knowing full well it’s bad for you. You want to stop, but you always come back.
“I don’t understand how she keeps coming back to that monster!”

“She’s feeling pernicious love.”
by Luca Simpson January 12, 2019
1.anatomical feature in some females of the human species whereby their genitals overhang the boundaries of their clothing, causing damage to the crotch region of their pants.

2. camel toe} so obnoxiouly obvious that you can't help to stare (see Lady Gaga})
If it weren't for her pernicious camel toe, she wouldn't have to buy new jeans every 3 months.
by El on Wheels April 5, 2010