look up any word, like wyd:
 
1.
Sexy, particularly as relates to sex with anthropomorphised animals, cartoon animals, or sentient animals, any of which may be known as a furry. From yiff.
That vixen is yiffy.
by Benfold February 20, 2003
 
2.
(in furry fandom)
adj. 1. Horny, aroused; 2. Sexy or attractive sexually
1. "Oh God I'm yiffy."
2. "Did you see her? She was yiffy."
by Colin Ritter August 06, 2003
 
3.
Wanting to have sex in an animal costume with others in animal costumes.
I'm feeling Yiffy today, grab your costumes!
by Zombiefied December 18, 2013