rites...so ancient that they well might have had their unwritten origins in Aurignacian times.
Examples of unwritten
unwritten
Girls can sometimes get away with it, but its an unwritten rule that guys can't.
From the edeneatseverything.com
Or more likely, some as-yet-unwritten tale being dreamed up somewhere right now.
From the nytimes.com
The agency crafted a series of ads for Miller about the unwritten code for guys.
From the usatoday.com
No, professional sportspeople have an unwritten clause or two in their contract.
From the nzherald.co.nz
Any unwritten rules broken there and is Boll's back going to be an ongoing issue?
From the dispatch.com
The capital has had an unwritten compact with the national carrier for decades.
From the smh.com.au
The empty seat behind me is a silent reminder of the unwritten rule being broken.
From the smh.com.au
That's because baseball is a game with as many unwritten rules as written ones.
From the kansas.com
All are in that position because of the dynastic unwritten rules by the Congress.
From the economist.com
More examples
Based on custom rather than documentation; "an unwritten law"; "rites...so ancient that they well might have had their unwritten origins in Aurignacian times"- J.L.T.C.Spence
Oral: using speech rather than writing; "an oral tradition"; "an oral agreement"
Ad-lib: said or done without having been planned or written in advance; "he made a few ad-lib remarks"
Unwritten is the debut album released by pop singer Natasha Bedingfield. It was released in the UK on 6 September 2004, where it debuted at number one, and in the U.S. on 2 August 2005, where it debuted at number twenty-six. ...
House is scheduled to enter a seventh season on September 20, 2010. This season will address House and Cuddy's relationship. In Bulgaria, Nova Television will begin airing the seventh season on September 24, 2010, only four days after the original US-air.
"Unwritten" is a song by English singer Natasha Bedingfield. Bedingfield, Danielle Brisebois, and Wayne Rodriguez wrote it for her debut album, Unwritten. The single was released as the album's third UK single (Nov 2004) and second US single (2006). ...
The Unwritten is an American comic book ongoing series written by Mike Carey with art by Peter Gross and published by the Vertigo imprint of DC Comics. The book follows Tom Taylor, who was the inspiration for a series of hugely successful children's fantasy novels in the vein of Harry Potter. ...