(chiefly Britain, idiomatic) I am mistaken; I thought that what I said (or wrote) was true, but I have just realised that it is not.

Modern site of the ancient city of Akhetaten in Egypt, built by Akhenaten in honor of the Egyptian deity Aten.

(in response to a question) I don't know!

Used other than figuratively or idiomatically: see don't, tell, me. / (idiomatic) Used to introduce a guess at a fact or situation, as if forestalling the other speaker's utterance.

(colloquial) Introduces a compromise or arrangement where the interlocutor has some benefit or advantage.

plural of tell-tale compass

(sarcastic) Said to someone who has ill-conceived, false beliefs.

(US) A policy of the U.S. military from 1993 to 2011, which barred openly gay, lesbian, or bisexual people from serving in the military, while also barring discrimination against closeted gays, lesbians, and bisexuals.

(US, dated, colloquial, rhetorical question) A rhetorical question with the implied answer being that competitors do not share business secrets with one another.

A dead person can no longer reveal information, especially information which others wish to keep secret.