Green’s Dictionary of Slang

1. absolutely correct.

1970		Time 16 Mar. 4: Your ‘Catholic Exodus’ article was right on. We especially concur with the comments you published concerning secular employment.
1977		C. McFadden Serial 62: He [...] was immediately proved right on.
1984		Totally True Diaries of an Eighties Roller Queen 🌐 26 Aug. Tomorrow we’re getting a 26er [of vodka]. It’s going to be right on.
1999		G. Seal Lingo 104: groovy, cool, funky and right on seem to have made a comeback in 1990s youthspeak, presumably inspired by the revival of 1960s fashions and music.
2000		Guardian G2 17 May 22: I think he’s spot on. Right on it.

2. politically correct, ideologically pure; also as a n.

1970		Time 19 Oct. 45: Homans is known as a ‘right-on lawyer’—he defends blacks, war protesters and poor people.
1992		D. Jarman diary 30 Nov. Smiling in Slow Motion (2000) 270: The sex police are the vinegar dregs of the right-on, they set up structures with all the oppressive rhetoric of Catholic commands.
2004		C. Brookmyre Be My Enemy 144: The flowchart on some right-on feminazi pamphlet.
2012		(con. 1980s) I. Welsh Skagboys 190: Feelin as aliented fae the boys here as ah did the right-on students in Aberdeen.