adv. phr. About to say something, such as a name, a telephone number, etc., but unable to remember it for the moment. "His name is on the tip of my tongue," Tom said. "It will come to me in a minute."
ON THE TIP OF ONE'S TONGUE
Meaning of ON THE TIP OF ONE'S TONGUE in English
American idioms English vocabulary. Английский словарь американских идиом. 2012