Yiff

[Sarah]

(noun) Sound supposedly made by mating arctic foxes.
(acronym) (or more backronym) YIFF or Y. I. F. F. - Young Incredibly Fuckable Furry
(proper name) YIFF sound server. Program for Linux to help handle audio.
(noun) More or less (usually more) sexual act. Commonly used by [furries], usually denotes standard intercourse but may denote any kind of sexual behaviour between any type and number of parties (imaginary anthro creatures, humans, animals, even inanimate objects like plushies). Antonym: Yerf.
(verb) Like in meaning 4, to yiff.
Furry (or otherwise) artwork depicting yiff as in meaning 4.
Expression of joy (by furries)
Non-invasive question about sexual feelings/will to mate.

Note in all sexual meanings this has a very specific emotional background: Its neither considered vulgar (like fuck or technical (like have intercourse) or emotion-less (like make love). Its playful, considering the act like something fun, nice, pleasant and not very important - without any special obligations attached to it. Lets yiff has about the same emotional background as Lets play.
See also [yiffy]

[Britney]

It stands for, Yucky Idiotic Furry Fuckers. Y.I.F.F.

[PussyCat]

Yell Sniff = Yiff
Created by Stephanie Patrick on Game Theory Live.

[Little_Girl]

The Furry Fandoms word for Sexual Intercourse, where two furs have a sexual affair. The word originates from the noise a fox creates when it mates. The phrase is used for sexual acts universally involving furries, not just specific acts.

[Sonia]

A happy affirmation in an imaginary fox language, invented by the writer of the Fuzzball MUCK server. The definition was confused with the definition for another word in the same imaginary language, yipp, and an administrator of another MUCK heavily promoted yiff word in its first known sexual connotation in 1995 or later. It was only after this point that supposed origins concerning mating sounds and acronyms were invented.

Meant to imply feelings of sexual arousal or intent to arouse; also refers to a sexual act. Considered crass language in polite circles.

[Tina]

(Onomotopia.) A bark made by a fox when aroused. Usually referrs to the sound made by the male of the species.

[Sonia]

yelling and sniffing at the same time

[PussyCat]

to yell and sniff near-simultaneously

[Becky]

1.Young, Incredibly, Fuckable, Furries
2. A form of internet porn not unlike hentai that involves anthros (bipedal, walkin talkin animals, with human actions, facial expressions, and traits)that is usualy hand drawn
3. The noise a fox makes when mating
4. A very thouroughly slandered fandom throughout the internet by biased self religous try hards

[Gregory]

[Yiff] is the [hottest] type of porn because it is [furries] having sex