Green’s Dictionary of Slang

1. (orig. US) open, honest.

1966		(con. 1958) R. Farina Been Down So Long (1972) 98: It’s all in front, man, they have a heart thing going for them.
1968		T. Wolfe Electric Kool-Aid Acid Test (1969) 53: A community of intelligent, very open, out-front people — out front was a term everybody was using — out-front people who cared deeply for one another.
1970		E. Tidyman Shaft 126: Up front, baby. I’m up front with you.
1971		Current Sl. VI 8: Out front, adj. Sincere; honest.
1984		W.D. Myers Outside Shot 88: Teufel and Leeds wanted me to help them win games but not be too out front when I did it.
1989		T. Blacker Fixx 306: Our friend [...] being in fact a bit of a wimpo when it comes to an up-front confrontation.
1996		J. Byrell Lairs, Urgers & Coat-Tuggers 274: Ronald Arthur Casey the gloves-off, lisping, republican, bon vivant, radical philosopher and very up-front sports and sociology commentator.
1999		K. Sampson Powder 112: Both Tom and Malky had been very upfront, but they weren’t prepared to take less than their rate now.
2000		J.J. Connolly Layer Cake 110: Scousers are very similar to true Londoners, flash, up-front and knowing.
2008		R. Price Lush Life 169: Could we have been any more up-front about how it went down?
2020		C. Hiaasen Squeeze Me 75: ‘Knock it off. Wasn’t I up-front about my hitch in prison?’’.

2. in the foreground; foremost.

1973

Newsweek 19 Feb. 33: The up-front concern now is to improve economic and social conditions for blacks in the urban ghettos.