Green’s Dictionary of Slang

1. (Aus.) hesitant, unamenable.

1930

Referee (Sydney) 15 Oct. 3/5: Kingcraft' was very ‘iffy’ at the post. During the autumn his manners improved.

2. marginal, not wholly acceptable, unpalatable.

1940		Lavine & Wechsler War Propaganda and the US 59: Questions about the board’s work were ‘iffy’.
1956		J. Blake letter 25 Sept. in Joint (1972) 93: If I can ride this riff through the winter (and it’s iffy) I’ll stay here.
1968		G. Slatter Pagan Game (1969) 172: Bluffed the doctor over his iffy knee and had a marvellous tour.
1974		G.F. Newman You Flash Bastard 166: Yes, sir, I’ve read the proposals – they get through; it’ll be a step in the right direction. It’s all a bit iffy though.
1982		J. Sullivan ‘The Yellow Peril’ Only Fools and Horses [TV script] It’s bound to be a bit iffy innit, after 17 years?
1990		R. Doyle Snapper 33: She might get varicose veins [...] Better than iffy rectum veins, she thought.
1999		Guardian Guide 3–9 July 69: A slightly iffy trip down memory lane.
1999		P. Temple Black Tide (2012) [ebook] Be a bit iffy when it gets dark.
2000		T. Blacker Kill Your Darlings 245: The iffy games they used to play on some of the tastier girls.
2007		S. Maloney Sucked In 115: The weather was looking iffy.
2012		D. O’Donnell Locked Ward (2013) 324: It’s like, totally iffy Karma for you to be in here.
2013		J. Stahl Happy Mutant Baby Pills 146: A mysterious junkie waif with iffy greeting card credentials who might have been black ops.
2023		(con. 1962) J. Ellroy Enchanters 55: ‘House bugs are always an iffy proposition’.

3. involved with criminality.

1989		M. Amis London Fields 89: John Dark, the corrupt policeman – the bent copper, the tarnished badge, the iffy filth.
2005		B. Hare Urban Grimshaw 147: Most people thought me ‘dodgy’, ‘iffy’, some said.

4. difficult.

1986		F. Taylor Auf Wiedersehen Pet Two 102: Oh? Bit iffy, is it?
1990		J. Wambaugh Golden Orange (1991) 58: Besides, disks’re iffy no matter what.
2001		K. Sampson Outlaws (ms.) 133: Just a little bit of comp for them in case the company decides to get iffy.
2007		N. ‘Razor’ Smith Raiders 41: The get-away was going to be a bit iffy.
2018		G. Gilmore Base Nature [ebook] ‘The bank [...] got a bit iffy when I couldn’ tell them my phone ID’.
2021		T. Swerdlow Straight Dope [ebook] DreamWorks was one of the co-producers. So, it’s already a little iffy with them.

5. ambiguous, thus iffiness, ambiguity, uncertainty.

1986		C. Stroud Close Pursuit (1988) 158: Some of the bosses had made it clear that an iffy call between murder and suicide could be called suicide.
2019		D. Winslow Border [ebook] You’ve never been in the system, you don’t know. It’s iffy. Could go either way. You get the wrong judge, he’s having a bad day.
2021		L. McInerney Rules of Revelation 349: Besides [...] being confronted like that, would have made her iffy even if she’d been adamant.
2022		J. Hannaham Didn’t Nobody Give a Shit 31: Carlotta smiled like a fool, trying to hide her iffiness and doubt.